Este desafío es encontrar la cadena más larga de palabras en inglés donde los primeros 3 caracteres de la siguiente palabra coincidan con los últimos 3 caracteres de la última palabra. Utilizará un diccionario común disponible en distribuciones de Linux que se puede descargar aquí:

https://www.dropbox.com/s/8tyzf94ps37tzp7/words?dl=0

que tiene 99171 palabras en inglés. Si su Linux local/usr/share/dict/words es el mismo archivo (tiene md5sum == cbbcded3dc3b61ad50c4e36f79c37084), puede usarlo.

Las palabras solo pueden usarse una vez en una respuesta.

EDITAR: letras deben coincidir exactamente incluyendo mayúsculas / minúsculas, apóstrofes y acentos.

Un ejemplo de una respuesta válida es: idea deadpan panoramic micra craftsman mantra traffic fiche que obtendría 8.

La respuesta con la cadena de palabras válida más larga será la ganadora. En caso de empate, la primera respuesta ganará. Su respuesta debe enumerar la cadena de palabras que ha encontrado y (por supuesto) el programa que escribió para hacerlo.

Java, heurística que favorece el vértice que induce el gráfico más grande: 1825 1855 1873

El siguiente código se ejecuta en menos de 10 minutos y encuentra la siguiente ruta:

[wad, wadis, dis, dismay, may, mayfly, flywheels, elsewhere, erecting, ingratiate, ateliers, ersatzes, zest, esthetic, tickled, ledger, germicide, idealizes, zestful, fulling, ingrains, institute, uterine, ineptness, essaying, ingeniously, slyness, essences, cessations, onshore, ores, resoundingly, glycerine, inertness, essay, say, saying, ingenuous, ousted, tediously, sly, slyest, estrogen, genuflecting, ingestion, ionizer, zeros, roses, sesames, mes, meshed, hedonist, isthmuses, sesame, amending, ingredient, entrapment, enthuses, session, ionosphere, erectness, essayist, isthmus, mustaches, hesitatingly, glycogen, generation, ions, onset, settable, blew, lewder, deriding, ingratiates, testicles, lessen, sensitization, ionization, ionizing, ingratiating, ingenious, ouster, terrorizing, ingest, estranges, gesticulating, ingrates, testis, tissue, sue, suede, edelweiss, issuing, ingraining, ingrown, owner, nerdiest, estimation, ionospheres, rescue, cue, cueing, ingesting, ingot, got, gotten, tensor, sorrowing, ingratiated, tedious, ousting, ingratiatingly, glycerin, ringside, identifiable, bleariest, ester, terminological, calibrator, torrent, entraps, apse, pseudonym, nymphomania, niacin, cinema, emailed, led, ledges, gesticulates, testicle, clement, entail, ail, ailment, enter, terrains, inspires, restaurateur, euros, rosiest, estimates, tester, termite, iterator, torture, urethras, raspiest, estimator, tore, oregano, anointment, enthuse, useful, fulfil, filmstrip, riposte, stereotyped, pedicure, urea, readmits, itself, elf, elfin, finagles, lesbians, answerable, bleat, eatery, erythrocytes, testosterone, one, ones, nest, esteemed, medicine, inextricable, blessed, sediment, entry, try, tryout, outsources, cesarians, answered, redressed, seducer, cervical, calumniates, test, establishment, entombment, enthusiastic, tickles, lessens, ensemble, blemishes, hesitant, antic, tick, ickiest, estimable, blemished, hedgehog, hogan, gantlet, letdown, own, ownership, hippest, estates, testates, testiest, establishes, hes, hesitates, testable, bleakest, esthetes, testament, entice, iceberg, erg, ergonomic, microscope, operatives, vestibules, lesser, serenade, adenoidal, dales, lest, estrangement, entrap, raptures, resourceful, fulsome, omen, menswear, earthliest, established, hedges, gestates, testy, styes, yeshivot, voter, terrible, blender, derides, descent, enticed, cedillas, lass, assailable, bleacher, hermit, mite, item, temperas, rash, ashtray, rayon, yonder, dermis, mismanage, agendas, dash, ashy, shy, shyster, terrapins, insatiable, bleeder, derives, vestment, entangle, glen, lengthens, ensconced, ceded, deduced, cedars, arsenic, nice, ice, iced, cedar, daredevil, villa, llamas, masseuse, use, useable, bleach, achievable, bleached, hedonistic, tic, ticker, kerchieves, vessel, sell, ell, elliptic, ticket, kettles, lessee, seeps, epsilon, longboat, oath, atherosclerosis, sisterhood, oodles, lesson, sonatas, tassel, selvage, age, agent, entranced, cedes, descender, deranges, gestures, restraint, interment, enthused, seduced, cedilla, llama, amalgam, gamut, mutable, blend, endear, earthy, thymus, mussel, seltzer, zero, erodes, despot, potful, fulfillment, enthrall, allot, lotus, tussle, sledgehammered, redolent, entrapped, pedestal, talk, alkalis, listen, tended, deductible, bleeped, pedigree, reentered, redistribute, uterus, rustproofed, fed, fedora, oranges, gesundheit, either, herdsman, manes, nestles, lessor, sorrowful, fullback, acknowledges, gestured, redoubtable, blended, deduces, cesareans, answer, werewolves, vesper, perseveres, restructures, reside, ideogram, rammed, meddlesome, omens, ensign, ignores, restrains, insolent, entanglement, entrenchment, enticement, entomological, calligraphy, physical, calico, iconoclast, astringent, entertainment, entrant, antennas, nasty, stymie, miens, enslave, averred, redefine, inexorable, blenched, hedgerow, rowboat, oat, oaten, tend, endears, arson, songwriter, terminable, blent, entreaty, atypical, calypso, psoriasis, sister, term, ermine, ineligible, bleaker, kerosene, enema, emancipator, tormentor, torrider, derailment, entertains, instil, tildes, destine, inelegant, anthropomorphic, hiccup, cupolas, lastingly, glycerol, rollback, acknowledgment, entombed, bedridden, denser, servicewomen, menopause, used, sedatives, vesicle, clearinghouse, user, servant, antipodes, descry, crystalline, inexpedient, enthusiast, astonishment, entirety, etymological, calendared, redbreast, astronomer, merinos, nosedove, overpay, pay, paymaster, termagant, antiaircraft, aftercare, ares, resentful, fulcrum, rumpus, pushcart, artiste, stethoscopes, pesetas, taste, steadfast, astride, ides, destitute, utensil, silvan, vanguard, ardent, entryway, waysides, despair, airdrop, ropes, pestered, redder, derangement, entered, redeemed, medullas, lasagnas, nasal, salsas, sashay, hay, haymow, mow, mowed, wedder, derringer, germane, anemic, microfilmed, media, diatom, tomboys, oyster, terminator, toreador, dorsal, salespeople, pleased, sedater, terabit, bitten, tentacle, clergyman, manifesto, stomach, achoo, hoopla, plaza, azalea, leaven, vendor, dormant, antiparticle, cleared, redraft, afterword, ordains, insufficient, entitlement, entomb, ombudsmen, men, mental, tallyhos, hospice, icecap, cape, aperitif, tiffed, fedoras, rasped, pediatric, rickshaw, hawker, keratin, tinctures, reset, setback, acknowledgement, enthronement, entwine, inexact, actor, torpedos, dosed, sedan, dancer, cerebrum, rumple, plea, leach, ache, cheaper, per, periscopes, pestilent, entreat, eater, terser, serape, ape, apes, pesky, skycap, capped, pederast, astuter, terrace, acetaminophen, henchmen, menopausal, saltcellar, lard, ardor, dormice, icebound, underbrush, ushered, redrew, rewound, underclass, assassin, sinew, newscast, astrologer, gerund, undertaken, ken, kens, ensnared, redcap, cappuccinos, nostrum, rum, rumored, redraw, rawhide, identical, calcine, inertia, tiara, arabesque, queerer, reruns, unsold, oldie, diesel, selectmen, mentored, redden, dental, talon, longhand, and, androgen, genome, omelet, lethal, hallucinogenic, nickname, amen, menhaden, denudes, despaired, redevelop, lope, operas, rasp, aspired, redskin, kindergartens, ensnares, resultant, anthropological, callus, lustful, fulcra, crammed, mediocre, crepes, pesticide, ideas, eastbound, under, derrières, respired, rediscovered, redundant, antihero, erode, ode, odes, described, bedevil, villager, gerrymander, deride, ideograph, aphid, hid, hides, describes, besides, despoil, oilskin, kingdom, dominant, ant, antipasti, stiffens, ensured, redeemer, merchant, antiwar, warped, pederasty, stylus, lush, usher, her, hereafter, terrapin, pinnacle, clerical, caliber, bereave, avenger, geriatric, rickshas, haste, stereoscopes, pester, termini, initiator, tortures, restorer, reran, ransomed, medulla, llanos, nostril, rill, illogical, calif, lifer, fervor, vortex, textures, resister, termed, medieval, valor, lord, ordered, rediscover, verbatim, times, mesdames, mescal, caliper, periscope, opera, erasures, restart, artichokes, kestrel, reliant, antebellum, lumbago, agog, goggle, gleeful, fulfill, illustrator, tor, torque, questionnaires, resumed, mediator, tort, orthodoxy, oxymora, oratorio, riot, iotas, taster, terrific, fiche, checkpoint, interloper, perfumes, mesas, sassafras, rasher, heraldry, drywall, all, allergens, ensnare, area, rearm, armchair, airman, manufactures, resurface, acerbic, bicycle, cleverer, rerun, runt, untidy, idyllic, lichens, ensures, resend, endemic, microchip, hippopotamus, muscatel, telecast, astronaut, autopilot, lot, loth, other, heros, rosin, single, gleamed, mediaeval, valet, lettered, redound, underside, ideological, calliper, perihelia, liaison, sonic, nicknames, messenger, germicides, descendant, antigen, genital, tall, allergen, gentleman, mangos, gossipped, pedicures, resistant, antlered, redeveloped, pedagogical, calligrapher, heroins, inside, idea, deafen, fen, fencer, cerebra, bravuras, rascal, calculus, lusher, herbivores, resins, instill, illicit, citric, ricochet, heterodoxy, oxygen, generic, rice, icebox, box, boxcar, cartography, physique, quell, ellipsis, sis, sisal, sallow, lowbrow, rowel, well, elliptical, calf, alfresco, scow, cow, cowboy, boy, boyfriend, end, endeared, red, redesign, ignoramus, musket, kettledrum, rump, umped, pedlar, larvas, vassal, salmonellas, last, astronomical, calfskin, kingfisher, hereupon, ponchos, hospital, talisman, mantel, telethon, honcho, chomped, pedant, antitoxins, instant, antipastos, tossup, superintend, endangered, redskins, instigator, torpor, portico, icon, conquistador, dormer, merganser, seraphic, hiccuped, pedagogue, guerrillas, laser, sera, eraser, seraph, aphasic, sickbed, bed, bedsores, resign, ignorant, anthropocentric, richer, herdsmen, menu, enures, resuscitator, tornado, ado, adobe, obeisant, anthill, illegal, gallon, longshoremen, menace, ace, acetylene, enemas, mas, mascot, cot, cotton, tonsures, restores, result, ultraviolet, letterbox, boxer, xerography, physiological, calmer, merchantmen, mentor, torus, russet, settee, teenager, gerbil, billfold, old, olden, denatures, resubmit, mitten, ten, tenon, nonchalant, antique, queasy, asymmetric, ricksha, shanghai, haircut, cutups, upsides, descriptor, torpid, pidgin, gins, instep, tepee, peeper, perturb, urbane, anemia, miasmas, mascaras, raspy, spy, spyglass, assures, resonator, tortilla, llano, anon, nontechnical, calabash, ashram, rampart, arthropod, podia, diagram, ramp, amp, amphitheatres, resistor, tortillas, lasagna, gnat, natal, talc, alcoholic, licensee, seemed, medical, calm, almanac, nacho, choreography, phylum, lumbar, barman, mannequins, insures, respires, resound, underarm, armatures, resides, desideratum, tumult, ultrasound, underdog, dogcatcher, herald, alderwoman, mandarins, insecticides, desires, respirator, torrid, rid, rides, descant, anticlimax, maximum, mum, mummer, meringue, guesser, sermon, monogram, ramrod, rodeo, deodorant, antelopes, peso, esophagus, gusset, setups, upshot, hotel, telescope, open, penicillin, lingos, gossip, sip, siphon, honor, normal, maltreat, eaten, tenet, nether, herpes, pesticides, descend, endow, downfall, alleyway, way, waylay, layman, manicures, reshuffle, flea, lea, leash, ashen, henchman, mandolin, linchpins, inscribes, bestow, townspeople, plectrum, rumbas, baste, sternum, numb, umbilici, icicle, cleaver, vertebra, brains, insouciant, antidepressant, anthem, hemoglobin, binocular, largos, gossamer, mermaid, aid, aides, desperado, adopt, opt, optima, imam, mambos, bosun, sun, sunspot, potpourris, risky, sky, skyscraper, perturbed, bedraggle, glee, lee, leech, echo, choreographer, heraldic, dictum, tumid, midday, day, daybed, bedsides, desktop, topknot, notepaper, periodical, calendar, dare, areas, easel, selfsame, amebas, basins, ins, insulin, linnet, nettlesome, omegas, gasp, aspartame, amend, endures, researcher, herbal, balsas, sass, assault, ultimatum, tumor, mortgagor, gores, resort, orthopaedic, dictatorship, hipper, person, sonar, narc, arc, archduke, ukelele, elegant, anther, hereabout, outfox, fox, foxtrot, rotogravures, restaurant, antechamber, beret, retriever, verbena, enamor, morsel, sellout, outmaneuver, vertical, call, allergenic, niche, chessman, mandolins, insipid, pidgins, install, allures, rescind, indignant, antithetical, calicos, cosmonaut, auto, utopia, piano, another, heretical, calk, alkali, alibi, ibis, bistro, troupe, upend, endorser, serviceman, mandarin, rind, inductee, teepee, pee, peekaboo, bootstrap, rape, apertures, resin, singular, larval, valiant, antiperspirant, antipasto, stop, topical, calisthenic, nicer, cervix, vixen, xenophobic, bicep, cephalic, licit, citizenship, hippopotami, amigos, gospel, pellet, letups, upstart, artificer, cerebellum, lumberman, manic, nicknamed, medic, dickie, kielbasas, sash, ash, ashcan, cannon, nonskid, kid, kidnaper, perjures, resolver, vernacular, larkspur, puree, reefer, ferret, retains, insofar, far, fart, artisan, sandbag, bagel, gelatin, tinsel, selectman, manacle, clever, versus, sustains, inscribed, bedpan, pandemic, microprocessor, sorbet, bet, betcha, char, harem, remodel, deli, elicit, citadel, deliver, verandas, dashikis, kisser, servicemen, menthol, holiday, daydreamer, merchantman, manikins, insane, anew, newsprint, interwove, overreach, achieve, even, venom, nomad, mad, madrigal, gala, alarm, armpit, pitchman, manor, northbound, underbid, bidet, detox, toxemia, miasma, smarten, tenderloins, insult, ultra, travel, velvet, veteran, random, domino, inopportune, uneconomic, microbes, bestir, tiro, ironware, arena, enamel, melodramas, mastodon, don, donut, nut, nutmeg, meg, megalopolis, lissom, sombre, breathe, therefrom, romper, performer, merman, mangrove, overshadow, downcast, astir, tiros, rostra, trachea, heaven, ventricle, clergywoman, maneuver, verbal, ballad, ladyship, hippie, pie, piebald, alderman, manatee, teethe, thereupon, poncho, choicer, ceramic, microscopic, picayune, uneaten, tendon, donor, northeast, astound, underpass, assessor, sorghum, hum, human, mantra, trainee, needlepoint, interplay, laywoman, mannikin, kinsman, mantillas, lassie, sieve, ever, verdigris, risen, sensor, sorrel, relabel, belabor, borsch, schlep, leprechauns, unsnap, nap, napkin, kin, kingpin, pinkeye, eyeglass, assemblyman, manikin, kingship, hip, hippos, postpartum, tumbrel, relic, lichee, heehaw, haw, hawser, servicewoman, many, anyhow, howsoever, vertex, text, extra, trap, rap, rapper, periwig, wigwag, wag, wagon, gonorrhea, heave, aver, vermin, minesweeper, perplex, lexicon, congas, gastronomic, microfiche, cheapen, pentathlon, longhair, air, aircraft, aft, aftertaste, stem, tempos, postwar, war, wart, article, clear, earshot, hotshot, hotbed, bedlam, lam, lambkin, kindergarten, tenser, serum, rumor, mortar, tarmac, macabre, breech, echos, hostel, telescopic, pickerel, relay, laypeople, pleas, east, astronomic, micra, crackpot, pot, potato, atom, tombed, bedbug, bugaboo, bootleg, leg, legato, atop, topple, plethora, orangutang, angora, orangutan, tan, tandem, democrat, rat, rattan, tang, angry, gryphon, honeybee, bee, beeswax, waxen, xenon, nonplus, lustre, trellis, lisle, sleepwear, earwig, wig, wigwam, wampum, pummel, melanomas, massacre, cretin, tin, tint, interviewee, wee, weeper, persimmon, monsignori, origin, gingham, ham, hamper, pericardia, diarrhea, heartthrob, rob, robes, besom, sombreros, rosebud, bud, budgerigar, garret, retrodden, denim, nimbus, bus, bushel, helmet, metaphor, horsefly, flypaper, peritonea, near, ear, earlobes, bestowal, wall, allay, layout, outlast, astrakhan, handicapper, perusal, saltpetre, tremor, moribund, undercut, cut, cutoff, off, offal, falcon, con, consul, sultan, tannin, ninepin, pinball, allegro, grommet, metro, trot, rot, rotten, tenpin, pineapple, plectra, transit, sitar, tar, taro, arousal, salmon, moneybag, bagpipe, ipecac, cache, checkout, outrun, runaround, undersea, sea, sear, earache, cherub, rub, rubicund, underpin, pin, pint, intagli, glib, lib, libel, bellyache, cherubim, bimbos, bosuns, unsound, undertow, tow, towel, wellington, ton, tonsil, silicon, concoct, octet, tetrahedra, drachmae, maestri, tripos, possum, sum, sumac, macro, crocus, custom, tom, tomcat, catsup, sup, superstar, tarpaulin, linchpin, pinpoint, intercom, comet, met, metacarpus, pussycat, catastrophe, phenomenon, nonverbal, ballpoint, interurban, bani, animal, malt, altar, tartar, tarot, rotund, undergrad, radio, diocesan, sandbar, bar, barren, renewal, walkout, outstrip, ripen, pen, pencil, cilantro, trout, outran, rancor, corncob, cob, cobra, bra, brag, rag, ragas, gas, gasohol, holdout, output, put, putsch, schwas, was, waste, stereo, reoccur, cur, curb, urban, ban, bantam, tam, tamp, ampul, pullout, outwit, wit, withal, halo, alohas, hasp, asparagus, gusto, stove, overlap, lapel, pelvis, visit, sit, sitcom, compendia, diadem, demigod, god, goddam, dam, dampen, pennon, non, noncom, compel, pelican, cancan, can, cancel, celesta, starlit, lit, litmus, muscat, cat, catnap, naphtha, than, handcar, carpel, pellagra, grammar, mar, mariachi, chichi, chi, chimp, imp, impel, pelvic, vicar, car, caribou, bourgeoisie, siesta, stab, tab, tabu, abut, but, butterfat, fat, fathom, homespun, pun, puns, unsheathe, the, theorem, remove, overtax, tax, taxicab, cab, cabal, balsam, sambas, basal, salamis, missal, salt, altho, tho, thou, housebound, underground, underclassman, man, mannikins, insectivores, resonant, antelope, operator, torn, ornamental, tallow, low, lowered, reddens, enshrine, inefficient, entertainer, nerves, vestiges, gesturing, ingested, tediousness, essentials]

Ideas centrales

En Aproximación de rutas y ciclos dirigidos más largos , Bjorklund, Husfeldt y Khanna, Lecture Notes in Computer Science (2004), 222-233, los autores proponen que en los gráficos de expansores dispersos se puede encontrar un largo camino mediante una búsqueda codiciosa que selecciona en cada pase al vecino de la cola actual de la ruta que abarca el subgrafo más grande en G ', donde G' es el gráfico original con los vértices en la ruta actual eliminados. No estoy seguro de una buena manera de probar si un gráfico es un gráfico expansor, pero ciertamente estamos tratando con un gráfico disperso, y dado que su núcleo tiene aproximadamente 20000 vértices y tiene un diámetro de solo 15, debe tener un buen propiedades de expansión Entonces adopto esta heurística codiciosa.

Dado un gráfico G(V, E), podemos encontrar cuántos vértices son accesibles desde cada vértice usando Floyd-Warshall a Theta(V^3)tiempo, o usando el algoritmo de Johnson a Theta(V^2 lg V + VE)tiempo. Sin embargo, sé que estamos tratando con un gráfico que tiene un componente muy grande fuertemente conectado (SCC), por lo que adopto un enfoque diferente. Si identificamos SCCs utilizando el algoritmo de Tarjan, también obtenemos una clasificación topológica para el gráfico comprimido G_c(V_c, E_c), que será mucho más pequeño en el O(E)tiempo. Como G_ces un DAG, podemos calcular la accesibilidad G_ca O(V_c^2 + E_c)tiempo. (Posteriormente descubrí que esto se insinúa en el ejercicio 26-2.8 de CLR ).

Como el factor dominante en el tiempo de ejecución es E, lo optimizo insertando nodos ficticios para los prefijos / sufijos. Entonces, en lugar de 151 * 64 = 9664 bordes de palabras que terminan -res a palabras que comienzan con res- Tengo 151 bordes de palabras que terminan -res a # res # y 64 bordes de # res # a palabras que comienzan con res- .

Y finalmente, dado que cada búsqueda toma alrededor de 4 minutos en mi PC anterior, trato de combinar los resultados con rutas largas anteriores. Esto es mucho más rápido y apareció mi mejor solución actual.

Código

org/cheddarmonk/math/graph/Graph.java:

package org.cheddarmonk.math.graph;

import java.util.Set;

public interface Graph<V> {
    public Set<V> getAdjacent(V node);
    public double getWeight(V from, V to);
}

org/cheddarmonk/math/graph/MutableGraph.java:

package org.cheddarmonk.math.graph;

import java.util.*;

public class MutableGraph<V> implements Graph<V> {
    private Map<V, Map<V, Double>> edgesBySource = new HashMap<V, Map<V, Double>>();

    public void addEdge(V from, V to, double weight) {
        if (!edgesBySource.containsKey(to)) edgesBySource.put(to, new HashMap<V, Double>());
        Map<V, Double> e = edgesBySource.get(from);
        if (e == null) edgesBySource.put(from, e = new HashMap<V, Double>());
        if (e.containsKey(to)) throw new IllegalArgumentException("There is already an edge between the vertices");
        e.put(to, weight);
    }

    @Override
    public Set<V> getAdjacent(V node) {
        Map<V, Double> e = edgesBySource.get(node);
        if (e == null) throw new IllegalArgumentException("node doesn't appear to be in the graph");
        return Collections.unmodifiableSet(e.keySet());
    }

    @Override
    public double getWeight(V from, V to) {
        Map<V, Double> e = edgesBySource.get(from);
        if (e == null) throw new IllegalArgumentException("from doesn't appear to be in the graph");
        if (!edgesBySource.containsKey(to)) throw new IllegalArgumentException("to doesn't appear to be in the graph");

        Double c = e.get(to);
        return c == null ? 0 : c.doubleValue();
    }
}

org/cheddarmonk/math/graph/StronglyConnectedComponents.java:

package org.cheddarmonk.math.graph;

import java.util.*;

/**
* A helper class for finding the strongly connected components of a graph using Tarjan's algorithm.
* http://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
*/
public class StronglyConnectedComponents<V> {
    private final Graph<V> g;
    private List<Set<V>> topologicallySortedSccs = new ArrayList<Set<V>>();

    private final LinkedList<V> S = new LinkedList<V>();
    private final Set<V> S2 = new HashSet<V>();
    private final Map<V, Integer> index = new HashMap<V, Integer>();
    private final Map<V, Integer> lowlink = new HashMap<V, Integer>();

    private StronglyConnectedComponents(Graph<V> g) {
        this.g = g;
    }

    private void strongConnect(V v) {
        int idx = index.size();
        index.put(v, idx);
        lowlink.put(v, idx);

        S.push(v);
        S2.add(v);

        for (V w : g.getAdjacent(v)) {
            if (!index.containsKey(w)) {
                strongConnect(w);
                if (lowlink.get(w) < lowlink.get(v)) {
                    lowlink.put(v, lowlink.get(w));
                }
            }
            else if (S2.contains(w)) {
                if (index.get(w) < lowlink.get(v)) {
                    lowlink.put(v, index.get(w));
                }
            }
        }

        if (lowlink.get(v).equals(index.get(v))) {
            Set<V> scc = new HashSet<V>();
            V w;
            do {
                w = S.pop();
                S2.remove(w);
                scc.add(w);
            } while (!w.equals(v));

            topologicallySortedSccs.add(scc);
        }
    }

    public static <V> List<Set<V>> analyse(Graph<V> g, Set<V> sources) {
        if (g == null) throw new IllegalArgumentException("g");

        StronglyConnectedComponents<V> scc = new StronglyConnectedComponents<V>(g);
        for (V v : sources) {
            if (!scc.index.containsKey(v)) {
                scc.strongConnect(v);
            }
        }

        return scc.topologicallySortedSccs;
    }
}

org/cheddarmonk/ppcg/PPCG.java:

package org.cheddarmonk.ppcg;

import java.io.*;
import java.util.*;
import org.cheddarmonk.math.graph.*;

public class PPCG44922 {
    private static final String path = "/usr/share/dict/words";
    private static Set<String> allWords;
    private static Graph<String> fullGraph;

    public static void main(String[] args) {
        loadGraph();

        Random rnd = new Random();
        rnd.setSeed(8104951619088972997L);
        List<String> a = search(rnd);
        rnd.setSeed(-265860022884114241L);
        List<String> b = search(rnd);
        List<String> chain = spliceChains(a, b);
        System.out.println(chain.size());
        System.out.println(chain);
    }

    private static List<String> search(Random rnd) {
        List<String> chain = new ArrayList<String>();
        chain.add(selectOptimalReachabilityCount(fullGraph, allWords, rnd));
        while (true) {
            String tail = chain.get(chain.size() - 1);
            FilteredGraph g = new FilteredGraph(chain);

            // We know that tail only has one successor, so skip ahead.
            Set<String> candidates = new HashSet<String>(fullGraph.getAdjacent(suffix(tail)));
            candidates.removeAll(chain);
            if (candidates.isEmpty()) break;

            chain.add(selectOptimalReachabilityCount(g, candidates, rnd));
        }

        Iterator<String> it = chain.iterator();
        while (it.hasNext()) {
            if (it.next().charAt(0) == '#') it.remove();
        }
        return chain;
    }

    private static List<String> spliceChains(List<String> a, List<String> b) {
        Set<String> intersect = new HashSet<String>(b);
        intersect.retainAll(a);
        if (intersect.isEmpty()) return null;

        // Splice the longest bits. To avoid cycles, we look for intersection points which have the same set of reached intersection points.
        // Thus to get from one to the next we can take either route without violating the unique occurrence of each element in the spliced chain.
        Set<String> left = new HashSet<String>();
        Set<String> right = new HashSet<String>();
        List<String> newChain = new ArrayList<String>();

        // NB We assume that either a(0) and b(0) are the same or neither is in intersect.
        // This is a safe assumption in practice because they're both "wad".
        int idxA = 0, idxB = 0, nextA = 0, nextB = 0;
        while (idxA < a.size()) {
            nextA++;
            while (nextA < a.size() && !intersect.contains(a.get(nextA))) nextA++;
            String tailA = nextA < a.size() ? a.get(nextA) : "";
            left.add(tailA);

            nextB++;
            while (nextB < b.size() && !intersect.contains(b.get(nextB))) nextB++;
            String tailB = nextB < b.size() ? b.get(nextB) : "";
            right.add(tailB);

            if (left.equals(right) && tailA.equals(tailB)) {
                // We take the longer of idxA to nextA-1 or idxB to nextB - 1.
                if (nextA - idxA > nextB - idxB) newChain.addAll(a.subList(idxA, nextA));
                else newChain.addAll(b.subList(idxB, nextB));

                idxA = nextA;
                idxB = nextB;
            }
        }

        if (new HashSet<String>(newChain).size() == newChain.size()) return newChain;
        throw new IllegalStateException();
    }

    private static void loadGraph() {
        Set<String> words = new HashSet<String>();
        Set<String> prefixes = new HashSet<String>();
        Set<String> suffixes = new HashSet<String>();
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(path), "UTF-8"));
            String line;
            while ((line = br.readLine()) != null) {
                if (line.length() >= 3) {
                    words.add(line);
                    prefixes.add(prefix(line));
                    suffixes.add(suffix(line));
                }
            }
            br.close();
        }
        catch (IOException ioe) {
            throw new RuntimeException(ioe);
        }

        // Filter down to a core with decent reachability.
        prefixes.retainAll(suffixes);
        MutableGraph<String> g = new MutableGraph<String>();
        Iterator<String> it = words.iterator();
        while (it.hasNext()) {
            String line = it.next();
            if (prefixes.contains(prefix(line)) && prefixes.contains(suffix(line))) {
                // In the interests of keeping the number of edges down, I insert fake vertices.
                g.addEdge(prefix(line), line, 1);
                g.addEdge(line, suffix(line), 1);
            }
            else it.remove();
        }

        fullGraph = g;
        allWords = Collections.unmodifiableSet(words);
    }

    private static String prefix(String word) {
        return "#" + word.substring(0, 3) + "#";
    }

    private static String suffix(String word) {
        return "#" + word.substring(word.length() - 3, word.length()) + "#";
    }

    private static <V> Map<V, Integer> reachabilityCount(Graph<V> g, Set<V> sources) {
        List<Set<V>> sccs = StronglyConnectedComponents.analyse(g, sources);
        int n = sccs.size();

        // Within a strongly connected component, each vertex can reach each other vertex.
        // Then we need to also take into account the other SCCs which they can reach.
        // We can exploit the fact that we already have a topological sort of the DAG of SCCs to do this efficiently.
        Map<V, Integer> index = new HashMap<V, Integer>();
        for (int i = 0; i < n; i++) {
            for (V v : sccs.get(i)) index.put(v, i);
        }

        BitSet[] reachableSccs = new BitSet[n];
        Map<V, Integer> reachabilityCounts = new HashMap<V, Integer>();
        for (int i = 0; i < n; i++) {
            Set<V> scc = sccs.get(i);
            reachableSccs[i] = new BitSet(n);
            reachableSccs[i].set(i);
            for (V v : scc) {
                for (V w : g.getAdjacent(v)) {
                    int j = index.get(w);
                    if (j < i) reachableSccs[i].or(reachableSccs[j]);
                }
            }

            int count = 0;
            for (int j = reachableSccs[i].nextSetBit(0); j >= 0; j = reachableSccs[i].nextSetBit(j+1)) {
                count += sccs.get(j).size();
            }
            for (V v : scc) {
                reachabilityCounts.put(v, count);
            }
        }

        return reachabilityCounts;
    }

    private static <V extends Comparable<? super V>> V selectOptimalReachabilityCount(Graph<V> g, Set<V> candidates, Random rnd) {
        Map<V, Integer> r = reachabilityCount(g, candidates);

        int max = 0;
        List<V> attaining = new ArrayList<V>();
        for (V candidate : candidates) {
            int score = r.get(candidate);
            if (score > max) {
                max = score;
                attaining.clear();
            }
            if (score == max) attaining.add(candidate);
        }

        return selectRandom(attaining, rnd);
    }

    private static <T extends Comparable<? super T>> T selectRandom(Collection<T> elts, Random rnd) {
        List<T> deterministic = new ArrayList<T>(elts);
        Collections.sort(deterministic);
        Collections.shuffle(deterministic, rnd);
        return deterministic.get(0);
    }

    private static class FilteredGraph implements Graph<String> {
        private final Set<String> filteredVertices;

        public FilteredGraph(Collection<String> filteredVertices) {
            this.filteredVertices = new HashSet<String>(filteredVertices);
        }

        @Override
        public Set<String> getAdjacent(String node) {
            if (filteredVertices.contains(node)) return Collections.emptySet();

            Set<String> adj = new HashSet<String>(fullGraph.getAdjacent(node));
            adj.removeAll(filteredVertices);
            return adj;
        }

        @Override
        public double getWeight(String from, String to) {
            throw new RuntimeException("Not used");
        }
    }
}

Rubí, 1701

"Del" -> "ersatz's"( secuencia completa )

Tratar de encontrar la solución óptima resultó demasiado costoso a tiempo. Entonces, ¿por qué no elegir muestras aleatorias, almacenar en caché lo que podamos y esperar lo mejor?

Primero Hashse construye un mapa que asigna prefijos a mundos completos comenzando con ese prefijo (por ejemplo "the" => ["the", "them", "their", ...]). Luego, por cada palabra en la lista, sequencese llama al método . Obtiene las palabras que posiblemente podrían seguir del Hash, toma una muestra de 100y se llama recursivamente. La más larga se toma y se muestra con orgullo. La semilla para el RNG ( Random::DEFAULT) y la longitud de la secuencia también se muestran.

Tuve que ejecutar el programa varias veces para obtener un buen resultado. Este resultado particular se generó con semilla 328678850348335483228838046308296635426328678850348335483228838046308296635426.

Guión

require "json"

def prefix(word); word[0, 3];  end
def suffix(word); word[-3, 3]; end

def sequence(word, prefixes, skip)
  if SUBS.key?(word) && (SUBS[word] - skip) == SUBS[word]
    return SUBS[word]
  end

  skip         += [word] 
  suffix        = suffix(word)
  possibilities = (prefixes[suffix] ||= []) - skip

  if possibilities.empty?
    return [word]
  else
    sequences = possibilities.sample(100).map do |possibility|
      sequence(possibility, prefixes, skip)
    end

    return SUBS[word] = [word] + sequences.max_by(&:size)
  end
end

def correct?(sequence)
  once_only = sequence.all? { |y| sequence.count(y) == 1 }
  following = sequence.each_cons(2).all? { |a,b| a[-3,3] == b[0,3] }

  return once_only && following
end

words = open("words.txt", "r", &:read).split.select { |word| word.size >= 3 }

SUBS     = {}
PREFIXES = {}

# Built a Hash that maps prefixes to an Array of words starting with the prefix.
words.each do |word|
  prefix = prefix(word)

  PREFIXES[prefix] ||= []
  PREFIXES[prefix] << word
end

longest = [1]

words.each do |word|
  PREFIXES[prefix(word)].delete(word)

  sequence = sequence(word, PREFIXES, [word])

  if sequence.size > longest.size
    longest = sequence
  end
end

puts longest.inspect
puts 
puts "Generated with seed: #{Random::DEFAULT.seed}"
puts "Length: #{longest.size}"
puts "Correct: #{correct?(longest)}"

Puntuación: 1631 1662 palabras

['Aachen', 'hen', 'henceforward', 'ardor', 'dorsal', 'salmon', 'monolog', 'log', 'logjam', 
'jam', 'jamb', 'ambassador', 'dormouse', 'useable', 'bleeding', 'ingenious', 'ouster', 
'terminable', 'bleakness', 'essay', 'say', 'saying', 'ingress', 'essences', 'cession', 
....
....
'ionosphere', 'ere', 'erecting', 'ingratiating', 'ingrate', 'ate', 'ateliers', "ersatz's"]

Puede encontrar la secuencia completa aquí: http://pastebin.com/TfAvhP9X

No tengo el código fuente completo. Estaba probando diferentes enfoques. Pero aquí hay algunos fragmentos de código, que deberían ser capaces de generar una secuencia de aproximadamente la misma longitud. Lo siento, no es muy bonita.

Código (Python):

Primero, un preprocesamiento de los datos.

from collections import defaultdict

with open('words') as f:
    words = [line.strip() for line in f]
words = [word for word in words if len(word)>=3 and word[-2:]!="'s"]

word_connections = defaultdict(list)
for word in words:
    word_connections[word[:3]].append(word)

Luego definí una función recursiva (profundidad primera búsqueda).

global m
m=0
def find_chain(chain):
    s = set(word_connections[chain[-1][-3:]])-set(chain)
    if len(s)== 0:
        global m
        if len(chain) > m:
            m=len(chain)
            print(len(chain), chain)
    else:
        for w in s:
            if w not in chain:
                find_chain(chain + [w])

for word in words:
    find_chain([word])

Por supuesto, esto lleva demasiado tiempo. Pero después de un tiempo encontró una secuencia con 1090 elementos, y me detuve.

Lo siguiente que debe hacer es una búsqueda local. Para cada dos vecinos n1, n2 en la secuencia, trato de encontrar una secuencia que comience en n1 y termine en n2. Si existe tal secuencia, la inserto.

def tryimpove(chain, length, startvalue=0):
    s=set(chain)
    for i in range(startvalue,len(chain)-1):
        print(i)
        for sub in sorted(short_sequences([chain[i]],length,chain[i+1]),key=len,reverse=True):

            if len(s & set(sub))==1:
                chain[i:i+1]=sub
                print(i,'improved:',len(chain))
                return tryimpove(chain,length,i)
    return chain

def short_sequences(chain,length,end):
    if 2 <= len(chain):
        if chain[-1][-3:]==end[:3]:
            yield chain
    if len(chain) < length:
        s = set(word_connections[chain[-1][-3:]])-set(chain)
        for w in s:
            for i in short_sequences(chain + [w],length,end):
                yield i

for m in range(5, 100):
    seq = tryimpove(seq,m)

Por supuesto, también tuve que detener el programa manualmente.

PHP, 1742 1795

He estado jugando con PHP en esto. El truco definitivamente es eliminar la lista de alrededor de 20k que son realmente válidos, y simplemente tirar el resto. Mi programa hace esto iterativamente (algunas palabras que arroja en la primera iteración significan que otras ya no son válidas) al comienzo.

Mi código es horrible, usa una serie de variables globales, usa demasiada memoria (guarda una copia de la tabla de prefijos completa para cada iteración) y me llevó literalmente días encontrar mi mejor versión actual, pero aún se las arregla estar ganando, por ahora. Comienza bastante rápido pero se vuelve más y más lento a medida que pasa el tiempo.

<?php

  function show_list($list)
  {
      $st="";
      foreach ($list as $item => $blah)
      $st.="$item ";
      return rtrim($st);
  }

  function mysort($a,$b)
  {
      global $parts;
      $a_count=isset($parts[substr($a,-3,3)])?count($parts[substr($a,-3,3)]):0;
      $b_count=isset($parts[substr($b,-3,3)])?count($parts[substr($b,-3,3)]):0;
      return $b_count-$a_count;
  }  

  function recurse($line,$list,$parts)
  {
    global $lines; 
    global $max;
    global $finished;
    global $best;
    $end=substr($line,-3,3);
    $count=0;
    if ($finished)
        return;
    if (isset($parts[$end]))
    {
        $maxp=count($parts[$end])-1;
        if ($maxp<0)
            return;
        $randa=array();
        for ($a=1;$a<3;$a++)
        {
            $randa[mt_rand(0,$maxp)]=1;
        }
        $n=mt_rand(0,$maxp);

        foreach ($parts[$end] as $key => $endpart)
        {

            if (!isset($list[$endpart]))
            {
                $this_part=$parts[$end];
                unset($this_part[$key]);
                $new_parts=$parts;
                unset($new_parts[$end][$key]);
                $list[$endpart]=1;
                recurse($endpart,$list,$new_parts);
                unset($list[$endpart]);
            }
        }

    }
    $count=count($list);
    if ($count>$max)
    {
        //echo "current best: $count\n";
        file_put_contents('best.txt',show_list($list) . "\n",FILE_APPEND);
        $max=$count;
        $best=$list;
    }
  }

  function cull_lines(&$lines)
  {
      global $parts;
      do 
      {    
          $wordcount=count($lines);
          $parts=array();$end_parts=array();
          foreach ($lines as $line)
          {
              if (strlen($line)<3)
                continue;
              $parts[substr($line,0,3)][]=$line;
              if (strlen($line)>3)
                $end_parts[substr($line,-3,3)][]=$line;
          }
          foreach ($lines as $key => $line)
          {
              $end=substr($line,-3,3);
              if (strlen($line)<3 || !isset($parts[$end]) || !isset($end_parts[substr($line,0,3)] ) )
                unset($lines[$key]);
          }
          foreach ($parts as $part)
          {
            if (count($part)==1)
            {
                $source_part=mt_rand(0,count($part)-1);
                $this_part = substr($part[0],0,3);
                $this_min = 10000;
                $this_key = 0;
                if (strlen($part[$source_part])==3)
                {
                    foreach ($lines as $key => $line)
                    if ($line == $part[$source_part])
                    {
                            unset($lines[$key]);
                            break;
                    }
                }
                elseif (isset($end_parts[$this_part]))
                {
                    foreach ($end_parts[$this_part] as $key => $end_part)
                    {
                        if (isset($parts[substr($end_part,0,3)]))
                        {
                            $n=count($parts[substr($end_part,0,3)]);
                            if ($n<$this_min)
                            {
                                $this_min=$n;
                                $this_key=$key;    
                            }
                        }
                    }

                    foreach ($lines as $key => $line)
                    if ($line == $part[$source_part])
                    {
                            unset($lines[$key]);

                    }
                    elseif ($line == $end_parts[$this_part][$this_key])
                    {
                        $lines[$key].=' ' . $part[$source_part];
                    }
                }

            }
          }
          echo "$wordcount words left\n";
      }
      while ($wordcount!=count($lines));
  }

  ini_set('xdebug.max_nesting_level',10000);
  ini_set('memory_limit','1024M');
  $lines = explode("\n",file_get_contents('words.txt'));
  cull_lines($lines);
  $max=0;
  foreach ($parts as $key=>$part)
    usort($parts[$key],'mysort');    

  $n=count($lines);
  foreach ($lines as $rand => $blah)
  {
      if (mt_rand(0,$n)==1)
        break;
  }
  $rand=$lines[$rand];
  $line[$rand]=1;
  echo "Starting with $rand...\n";
  recurse($rand,$line,$parts);
  unset($line[$rand]);

?>

Una mejora obvia sería usar una palabra huérfana para el inicio y el final.

De todos modos, realmente no sé por qué mi lista de pastebin se movió a un comentario aquí, está de vuelta como un enlace a pastebin ya que ahora he incluido mi código.

http://pastebin.com/Mzs0XwjV

Python: 1702 - 1704 Artículos de - 1733 palabras

Usé un Dict para asignar todos los prefijos a todas las palabras, como

{
    "AOL" : [
        "AOL", "AOL's"
    ],...
    "oct" : [
         "octet","octets","octette's"
    ],...
}

Edite una pequeña mejora: eliminar todas las uselesspalabras al principio, si sus sufijos no están en la lista de prefijos (obviamente sería una palabra final)

Luego tome una palabra en la lista y explore el mapa de prefijos como un nodo de árbol

import sys, fileinput
def p(w):return w[:3]

class Computing:
    def __init__(_):
        _.wordData = []; _.prefixes = {}
        _.seq = []; _.bestAttempt = []
        _.stop = False
        for l in fileinput.input():
            word = l.strip()
            if len(word) > 2:_.wordData.append(_.addPfx(word, p(word)))
        _.rmUseless();_.rmUseless()
        _.fromI = 0; _.toI = len(_.wordData)

    def rmUseless(_):
        for w in _.wordData:
            if not w[-3:] in _.prefixes: _.wordData.remove(_.rmPfx(w,p(w)))

    def addPfx(_, w, px):
        if not px in _.prefixes:_.prefixes[px] = []
        _.prefixes[px].append(w)
        return w
    def rmPfx(_,w,px):
        _.prefixes[px].remove(w)
        if len(_.prefixes[px]) == 0:del _.prefixes[px];
        return w

    def findBestSequence(_):
        def pickItem():
            r = None
            if _.fromI < _.toI:r = _.wordData[_.toI-1];_.toI -= 1;
            return r
        while not _.stop:
            w = pickItem()
            if not w:break;
            _.seq = [_.rmPfx(w,p(w))]
            _.checkForNextWord()
            _.addPfx(w, p(w))

        print " ".join(_.bestAttempt)

    def checkForNextWord(_):
        _.stop = len(_.seq) >= 1733
        cw = _.seq[-1]
        if not _.stop:
            if cw[-3:] in _.prefixes:
                lW = []
                for word in _.prefixes[cw[-3:]]:
                    if not word[-3:] in lW:
                        _.seq.append(_.rmPfx(word,p(word)))
                        _.checkForNextWord()
                        if _.stop :break;
                        _.addPfx(_.seq.pop(), p(word))
                        lW.append(word[-3:])
                    if _.stop :break;
        if len(_.bestAttempt) < len(_.seq):_.bestAttempt = _.seq[:];

sys.setrecursionlimit(6000)
Computing().findBestSequence()

El programa necesita varias palabras para saber cuándo parar, se puede encontrar como 1733en el métodocheckForNextWord̀

El programa necesita la ruta del archivo como argumento

No muy pitónico, pero lo intenté.

Se tardó menos de 2 minutos en calcular esta secuencia: salida completa :

los estudios desalinizados comieron ateliers ... bendición estimando a los ingenuos éxters

Puntuación: 249 500 1001

Aachen -> gallina -> de aquí en adelante -> ardiente -> implicar -> ail -> enfermo -> led -> ledger -> gerbil -> bilateral -> rally -> ingenioso - -> expulsado -> tedioso -> expulsor -> terabit -> bit -> bitched -> hedgehog -> hog -> hogan -> ganso -> descarrilar -> alerones -> inicio -> conjunto -> retroceso -> reconocimiento -> implicado -> libros de contabilidad -> ersatzes -> ralladura -> establecido -> seto -> fila -> bote de remos -> avena - -> oaten -> diez -> tenable -> lejía -> dolor -> abaratar -> pluma -> penaliza -> entusiasta -> fulcra -> cangrejo -> rabínico -> calabaza -> ceniza -> avergonzado -> medalla -> dale -> ale -> alertado -> tediosamente -> astuto ->astuto -> establece -> hes -> vacilante -> hormiga -> antiácido -> sidra -> descarrilado -> repisas -> gestado -> tedio -> ensayo -> decir - -> diciendo -> ingeniosamente -> astucia -> ensayo -> ingenuo -> expulsión -> ingenuidad -> ensayista -> istmo -> muscat -> gato -> cataclísmico -> ratones -> hielo -> iceberg -> erg -> ergonómico -> micra -> cangrejo de cama -> cama -> deslumbramiento -> lesbianas -> respuesta -> eran -> ere - -> erección -> ingestión -> establecimiento -> ingestión -> ingestión -> ion -> ionización -> ionizador -> cero -> erosión -> oda -> odas -> desaliniza -> prueba -> establecimiento - -> que entraña -> lingote -> conseguido -> conseguido ->inquilino -> antagonista -> istmos -> sésamo -> amebas -> basal -> salaamed -> medallón -> ionizante -> arrastre -> arrastre -> ins -> loco - -> anecdótico -> talco -> alcohol -> retención -> viejo -> antiguo -> guarida -> desnaturalización -> urea -> alcance -> dolor -> setos -> gestados -> comprobables -> blanqueados -> cobertura -> ingratos -> testamento -> enredos -> relucientes -> medallones -> en tierra -> minerales -> orégano -> ánodos - -> desalinizar -> congratula -> testates -> tester -> terabits -> its -> sí mismo -> elf -> elfin -> aleta -> finagle -> reluciente -> congratulante -> congratulante -> glicerina -> corteza -> endeudamiento -> esencias ->cesáreas -> responda -> blanqueador -> ella -> heraldo -> aliso -> descarrilamiento -> ingrediente -> enredo -> enredos -> lesión -> ionosfera -> erección - -> ionosferas -> reventa -> alerta -> entradas -> sésamo -> mes -> mesas -> faja -> ashcan -> lata -> canard -> ardor -> más tonto -> fincas -> testículos -> testículo -> limpiador -> más nerd -> estimado -> entrometidos -> arrendatario -> ver -> sembrado -> dedicado -> testículos - -> disminuir -> senates -> testificante -> estimación -> encarnado -> propio -> propietario -> nervios -> vesícula -> más limpio -> éster -> terabytes -> testículo -> tejido -> sue - - ante -> edema -> emaciados ->testosterona -> uno -> unos -> nido -> estetos -> irritable -> orzuelo -> orzuelos -> sí -> yeshivas -> vascular -> alerces -> vacilante - -> glicerina -> no comestible -> blanqueadores -> duda -> testificando -> ingrato -> comió -> talleres

Aquí está mi código:

import sys
sys.setrecursionlimit(10000)
w=[i for i in open("words.txt").read().split("\n") if len(i)>=3 and "'" not in i]
b=[i[:3] for i in w]
e=[i[-3:] for i in w]
a=[i for i in zip(*(w,b,e))]
def pathfrom(i,a,l):
    longpath=[]
    for j in a:
        if j[1]==i[2]:
            r=pathfrom(j,[m for m in a if m!=j],l+1)
            path=[i]+r[0]
            if r[1]:
                return path,r[1]
            if len(path)>len(longpath):
                longpath=path
    if l>=250:
        return longpath,True
        sys.exit()
    return longpath,False
for i in a[:2]:
    print i
    p=pathfrom(i,[j for j in a if i!=j],1)
    if len(p)>len(chain_):
        chain_=p
        print p
    print p

Editar: 1001:

http://pastebin.com/yN0eXKZm

Editar: 500:

Aachen -> gallina -> de aquí en adelante -> ardiente -> implicar -> ail -> enfermo -> led -> ledger -> gerbil -> bilateral -> rally -> ingenioso - -> expulsado -> tedioso -> expulsor -> terabit -> bit -> bitched -> hedgehog -> hog -> hogan -> ganso -> descarrilar -> alerones -> inicio -> conjunto -> retroceso -> reconocimiento -> implicado -> libros de contabilidad -> ersatzes -> ralladura -> establecido -> seto -> fila -> bote de remos -> avena - -> oaten -> diez -> tenable -> lejía -> dolor -> abaratar -> pluma -> penaliza -> entusiasta -> fulcra -> cangrejo -> rabínico -> calabaza -> ceniza -> avergonzado -> medalla -> dale -> ale -> alertado -> tediosamente -> astuto ->astuto -> establece -> hes -> vacilante -> hormiga -> antiácido -> sidra -> descarrilado -> repisas -> gestado -> tedio -> ensayo -> decir - -> diciendo -> ingeniosamente -> astucia -> ensayo -> ingenuo -> expulsión -> ingenuidad -> ensayista -> istmo -> muscat -> gato -> cataclísmico -> ratones -> hielo -> iceberg -> erg -> ergonómico -> micra -> cangrejo de cama -> cama -> deslumbramiento -> lesbianas -> respuesta -> eran -> ere - -> erección -> ingestión -> establecimiento -> ingestión -> ingestión -> ion -> ionización -> ionizador -> cero -> erosión -> oda -> odas -> desaliniza -> prueba -> establecimiento - -> que entraña -> lingote -> conseguido -> conseguido ->inquilino -> antagonista -> istmos -> sésamo -> amebas -> basal -> salaamed -> medallón -> ionizante -> arrastre -> arrastre -> ins -> loco - -> anecdótico -> talco -> alcohol -> retención -> viejo -> antiguo -> guarida -> desnaturalización -> urea -> alcance -> dolor -> setos -> gestados -> comprobables -> blanqueados -> cobertura -> ingratos -> testamento -> enredos -> relucientes -> medallones -> en tierra -> minerales -> orégano -> ánodos - -> desalinizar -> congratula -> testates -> tester -> terabits -> its -> sí mismo -> elf -> elfin -> aleta -> finagle -> reluciente -> congratulante -> congratulante -> glicerina -> corteza -> endeudamiento -> esencias ->cesáreas -> responda -> blanqueador -> ella -> heraldo -> aliso -> descarrilamiento -> ingrediente -> enredo -> enredos -> lesión -> ionosfera -> erección - -> ionosferas -> reventa -> alerta -> entradas -> sésamo -> mes -> mesas -> faja -> ashcan -> lata -> canard -> ardor -> más tonto -> fincas -> testículos -> testículo -> limpiador -> más nerd -> estimado -> entrometidos -> arrendatario -> ver -> sembrado -> dedicado -> testículos - -> disminuir -> senates -> testificante -> estimación -> encarnado -> propio -> propietario -> nervios -> vesícula -> más limpio -> éster -> terabytes -> testículo -> tejido -> sue - - ante -> edema -> emaciados ->testosterona -> uno -> unos -> nido -> estetos -> irritable -> orzuelo -> orzuelos -> sí -> yeshivas -> vascular -> alerces -> vacilante - -> glicerina -> no comestible -> blanqueador -> queratina -> estaño -> tintura -> uretras -> bribón -> calamina -> ineducable -> más sombrío -> estético -> tic -> tick -> ickiest -> estimable -> bleariest -> estimator -> tor -> torched -> hedonistic -> ticker -> kerchieves -> vesicles -> lessens - -> instalado -> cedro -> reto -> son -> área -> accesible -> balido -> comer -> comestible -> sangrante -> descarrilamiento -> entrar -> término -> armiño -> inefable -> bleeped -> pedagog -> goggle -> gleans ->respondió -> rojo -> pecho rojo -> aster -> termagant -> antagonista -> boleto -> timbal -> ron -> rumbas -> basalto -> altar -> alquitrán - -> tarántulas -> lasaña -> más retorcida -> distanciamiento -> ingresado -> gorro rojo -> gorra -> capaz -> pitidos -> épsilon -> más solitario -> alejamientos -> señalado -> gorros rojos -> ábside -> seudónimo -> ninfomanía -> niacina -> cinchonas -> nasal -> vendible -> mezcla -> final -> peligro -> geriátrico - -> arroz -> helado -> engaña -> víspera -> por -> perambulator -> rasgado -> minerales -> reventas -> menor -> sueros -> era -> eras -> erupción cutánea -> ceniciento -> hombre de confianza -> hombre -> esposas -> más limpio ->estrógeno -> gendarmes -> mescal -> calcina -> ineficiente -> entretenido -> glicerol -> papel -> adelfa -> trastorno -> entretenimiento -> entretiene -> insaciable - -> mezclado -> deducido -> cedros -> arsénico -> agradable -> nevera -> caja -> furgón -> auto -> caracul -> cullender -> deranges -> gestos -> reprogramar -> lección -> hijo -> sonar -> narc -> arco -> arcade -> adenoidal -> valles -> arrendador -> sorbete -> apuesta - -> betaken -> ken -> kens -> conjunto -> licuadora -> deride -> idea -> diácono -> con -> cóncavo -> vengador -> germane -> anemia -> miaowed -> wed -> casado -> deducible -> blent - -> cautivar ->all -> allay -> lay -> layaway -> way -> wayfarer -> reran -> ran -> rancher -> heralded -> deductible -> blessed -> sedan - -> bailó -> cedes -> desinfectante -> oso hormiguero -> denominado -> entrometido -> omegas -> gas -> herida -> ashram -> ram -> divagación -> sopló -> lewder -> derides -> descender -> en peligro de extinción -> redcoat -> juramento -> aterosclerosis -> sis -> sisal - -> ensalada -> muchacho -> escalera - -> derivados -> recipiente -> rara vez -> dominios -> inscrito -> chinche -> error -> bugaboo -> boo -> boobed -> bedder -> deriva -> vestigios -> gesundheit -> ya sea -> heráldico -> dados -> rompehielos -> queroseno -> enema -> correo electrónico ->dolencia -> entronización -> entusiasmo -> uso -> usado -> sedante -> terminador -> toreador -> latente -> antebellum - -> lumbago -> ago -> agonizante - -> glucógeno -> género -> dermis -> desventuras -> rescindir -> indecente -> entusiasmado -> sedantes -> vestimenta -> entusiasta -> astir -> diatribas -> descendiente -> antecedente -> atraer -> capa de hielo -> condensador -> tormento -> atraído -> cedilla -> llama -> amalgama -> gambito -> perras -> duda - -> testificar -> ingrato -> comió -> talleresgénero -> dermis -> desventuras -> rescindir -> indecente -> entusiasmado -> sedantes -> vestimenta -> entusiasta -> astir -> diatribas -> descendiente -> antecedente - -> atraer -> capa de hielo -> condensador -> tormento -> atraído -> cedilla -> llama -> amalgama -> gambito -> perras -> duda -> testificando -> ingrato -> comió -> ateliersgénero -> dermis -> desventuras -> rescindir -> indecente -> entusiasmado -> sedantes -> vestimenta -> entusiasta -> astir -> diatribas -> descendiente -> antecedente - -> atraer -> capa de hielo -> condensador -> tormento -> atraído -> cedilla -> llama -> amalgama -> gambito -> perras -> duda -> testificando -> ingrato -> comió -> ateliers

Mathematica 1482 1655

Algo para comenzar ...

dict=Import["words.txt"];
words=Union@Select[StringSplit[dict],(StringFreeQ[#,"'s"])\[And]StringLength[#]>2
  \[And]LowerCaseQ@StringTake[#,1]&]

Los enlaces son los prefijos y sufijos de intersección de palabras.

prefixes=Union[StringTake[#,3]&/@words];
suffixes=Union[StringTake[#,-3]&/@words];
links=Intersection[prefixes,suffixes];
linkableWords=(wds=RandomSample@Select[words,MemberQ[links,StringTake[#,3]]\[And]MemberQ[links,StringTake[#,-3]]& ])/.
w_String:> {w,StringTake[w,3],StringTake[w,-3]}

Los bordes son todos los enlaces dirigidos de una palabra a otras palabras:

edges[{w_,fr_,fin_}]:= Cases[linkableWords,{w1_,fin,_}:> (w\[DirectedEdge]w1)]
allEdges=Flatten[edges/@linkableWords];
g=Graph@allEdges;

Encuentre un camino entre "reparar" y "entusiasmo".

FindPath[g, "begin", "end", {1480, 3000}, 1][[1]]

Resultado (1655 palabras)

{"mend", "endorser", "server", "vertebral", "rallying", "ingrains", 
"insurrectionist", "isthmus", "mussels", "elsewhere", "erection", 
"ionizes", "zestful", "fullness", "essaying", "ingeniously", 
"slyest", "estimator", "tornados", "doses", "sesame", "amebic", 
"bicycled", "ledges", "gestation", "ionizing", "ingratiates", 
"testifying", "ingesting", "inglorious", "ouster", "terminated", 
"tediousness", "essayist", "isthmuses", "session", "ion", 
"ionization", "ionospheres", "resubmitted", "tedious", "ousting", 
"ingest", "ester", "terminates", "testicle", "cleanliness", "essay", 
"say", "saying", "ingratiating", "ingratiatingly", "glycerine", 
"inefficient", "entrances", "cesarians", "answering", "ingenious", 
"ousted", "tediously", "sly", "slyness", "essences", "cesareans", 
"answer", "were", "erecting", "ingredient", "enterprises", 
"sessions", "onshore", "oregano", "anorak", "raking", "ingraining", 
"ingrown", "owner", "nerdiest", "estranging", "ingot", "gotten", 
"tendonitis", "tissue", "suede", "edelweiss", "issuing", "ingestion", 
"ionosphere", "erections", "onset", "settles", "lesion", "ionizer", 
"zeroing", "ingresses", "sesames", "mesmerizing", "ingrates", 
"testes", "testiest", "estrangement", "entail", "ail", "ailment", 
"entice", "icecap", "captivates", "testy", "sty", "stylistic", 
"tickles", "lessee", "seeded", "deductibles", "lesser", 
"servicewoman", "many", "anymore", "ores", "resourceful", "fullback", 
"acknowledgment", "entertainer", "nerves", "vest", "esteemed", 
"mediates", "testament", "entered", "redbreast", "astonishes", 
"hesitatingly", "glycogen", "genera", "eras", "rashes", "hesitates", 
"testicles", "lest", "establishment", "entwines", "nest", "estates", 
"testates", "testosterone", "oneself", "elf", "elfin", "fingered", 
"redcaps", "apse", "pseudonym", "nymphomania", "niacin", "cinemas", 
"masochistic", "tickled", "led", "ledger", "geriatric", "rice", 
"icebreaker", "kerosine", "inexperienced", "ceded", "deductible", 
"blew", "lewder", "derivable", "blemished", "hedgerow", "rowel", 
"welfare", "arena", "enamel", "melded", "dedicates", "tester", 
"terabit", "bitmap", "mapped", "pedicures", "restored", "redeemer", 
"merchantman", "manipulator", "torpedos", "dosed", "seduced", 
"cedilla", "llano", "another", "heretic", "tic", "ticker", "keratin", 
"tinctures", "restaurateur", "euros", "rosettes", "testable", 
"bleaker", "kerosene", "energizer", "zero", "eroded", "deduced", 
"cedar", "dare", "ares", "respondent", "entranced", "cedillas", 
"lasagnas", "nastiest", "esthetic", "ticket", "ketches", "hes", 
"hesitant", "antipasto", "stoppered", "redounded", "deducible", 
"bleeped", "pedant", "antimatter", "terminable", "blent", "enthuse", 
"user", "serenade", "adenoidal", "dales", "lessen", "sentimental", 
"talker", "kerchieves", "vestry", "try", "tryout", "outdone", "ones", 
"nestles", "lesson", "songwriter", "terrapin", "pinched", 
"hedonistic", "tick", "ickiest", "established", "hedgehog", "hogan", 
"gander", "derringer", "gerbil", "billboard", "ardor", "dorkiest", 
"estrogen", "gent", "entirety", "etymological", "calk", "alkalis", 
"lissome", "omegas", "gasolene", "enema", "emaciates", "test", 
"estranges", "gestured", "redeemed", "medic", "diced", "cedars", 
"arsenic", "nice", "iceberg", "erg", "ergonomic", "microcomputer", 
"terser", "sergeant", "antipastos", "tost", "osteopathy", "thy", 
"thymus", "mussiest", "estimable", "blend", "endeavored", "redound", 
"undercover", "verbal", "balk", "alkali", "alibi", "ibis", "bison", 
"sonar", "narcosis", "sister", "terraced", "cede", "edema", 
"emancipator", "torpor", "portraiture", "urea", "reassign", 
"ignoble", "blenched", "hedges", "gesture", "urethras", "raspy", 
"spyglass", "ass", "assailant", "antiquarians", "answered", 
"reduced", "cedes", "despair", "airfares", "resumed", "medicine", 
"ineffable", "bleacher", "herdsmen", "menhaden", "dent", 
"entitlement", "enticement", "entangle", "gleamed", "medullas", 
"lassie", "sieve", "even", "vender", "derivatives", "vessel", 
"selectmen", "mentor", "toreador", "dormer", "meringue", "guerrilla", 
"llanos", "nosedove", "overact", "actionable", "bleeps", "epsilon", 
"longhorn", "ornament", "entreaty", "atypical", "calendar", "dares", 
"resurgent", "entreat", "eater", "term", "ermine", "inedible", 
"bleeder", "derrières", "resentful", "fulcra", "crabbed", 
"bedevilment", "entwine", "inelegant", "antitoxins", "inspired", 
"redder", "derides", "descendant", "antihistamine", "inequitable", 
"bleat", "eaten", "tenured", "redcap", "capstans", "answerable", 
"blender", "deranges", "gestures", "restart", "arteriosclerosis", 
"sis", "sisal", "saltpeter", "terrifyingly", "glycerin", "rink", 
"inkwell", "ellipsis", "sisterhood", "oodles", "lessor", "sorrowed", 
"wedges", "gesundheit", "either", "hereafter", "termite", "iterator", 
"tornado", "adobes", "bespoken", "ken", "kens", "ensnare", "area", 
"rear", "earful", "fulfil", "fillet", "letdown", "ownership", 
"hipped", "pediatric", "richer", "heretical", "calculus", "lusher", 
"heraldic", "dice", "icebound", "underscored", "redskins", "instant", 
"antiperspirant", "anthropomorphic", "hiccup", "cup", "cups", 
"upstage", "agendas", "dashingly", "glycerol", "role", "oleo", 
"leonine", "ineluctable", "blessed", "sedatives", "vesicles", 
"lessens", "ensured", "redefine", "inextinguishable", "bleach", 
"achoo", "hooch", "ocher", "hero", "erode", "ode", "odes", "desktop", 
"topple", "pleasured", "redeveloped", "pediment", "entrapped", 
"pederasty", "stylus", "lush", "usher", "hermaphrodite", "item", 
"tempos", "postpaid", "aide", "ideogram", "rampart", "artisan", 
"sandhog", "hog", "hogwash", "ash", "ashram", "rammed", "mediocre", 
"crestfallen", "lend", "endow", "downcast", "astronomer", 
"merriment", "entrant", "antiwar", "warden", "dentures", "restful", 
"fulfillment", "entrapment", "enthrall", "allay", "layout", 
"outbound", "underclassman", "manhole", "oleander", "dermis", 
"misused", "sedater", "terrific", "fiche", "cheapens", "ensnares", 
"restrains", "insolent", "entombed", "bedraggle", "gleeful", 
"fulfilment", "entrenchment", "entrap", "rapper", "persistent", 
"enthronement", "enthusiast", "astute", "uterus", "rustproofed", 
"fedora", "orangeades", "despised", "seducer", "ceramic", 
"microscopic", "picnic", "nicotine", "inexpedient", "entomb", 
"ombudsman", "mantel", "teletypewriter", "terminological", "calif", 
"lifetimes", "mescaline", "inertia", "tiaras", "raster", "terrace", 
"acetaminophen", "henchmen", "menhadens", "enslaves", "vesper", 
"peroxide", "ideograph", "aphid", "hides", "desideratum", "tumor", 
"mortgagee", "geegaw", "gawk", "awkward", "ardent", "enthused", 
"sediment", "enter", "termed", "mediaeval", "valentine", "inexact", 
"actives", "vestment", "entourage", "agent", "entryway", "wayside", 
"idea", "dear", "earache", "checkups", "upsides", "descent", 
"entertainment", "entomological", "calicos", "cosign", "ignored", 
"redcoat", "oaten", "tensed", "sedan", "dank", "anklet", "lettered", 
"redskin", "kingpin", "pinups", "ups", "upshot", "hotbed", 
"bedtimes", "mes", "messenger", "germicides", "destitute", "utensil", 
"silencer", "cervix", "vixens", "ensign", "ignorant", "antipasti", 
"stimulus", "lusty", "stymie", "miens", "enslave", "averred", 
"redrew", "rewritten", "tenpins", "instructor", "torrent", 
"entertains", "insult", "ultrasound", "undersides", "despoil", 
"oilcloth", "other", "hereupon", "pondered", "redundant", "anthill", 
"ill", "illicit", "citizens", "ensnared", "rediscovered", "redesign", 
"ignoramus", "muskmelon", "longer", "gerrymander", "deride", "ideas", 
"easy", "asylum", "lumbermen", "mendicant", "antlered", "redevelop", 
"lopes", "pester", "terrapins", "instil", "tildes", "deserves", 
"vesicle", "cleave", "avenger", "germane", "anemia", "miasmas", 
"mash", "ashy", "shy", "shyster", "termagant", "antiaircraft", 
"afterglow", "lowland", "and", "androgen", "genitalia", "liars", 
"arson", "sonatas", "taste", "stepsister", "termini", "initiator", 
"tor", "torn", "ornamental", "tallow", "lowered", "red", "redraft", 
"aft", "aftertaste", "stereotypes", "pesky", "skyrocket", 
"kettledrum", "rummer", "merciful", "fulsome", "omens", "ensures", 
"resultant", "antennas", "nasal", "saleswoman", "mane", "anemometer", 
"terrains", "insightful", "fulcrum", "rumbas", "baseman", 
"mannikins", "insures", "resound", "underpass", "assassins", "inset", 
"settee", "teethe", "theological", "calf", "alfresco", "scornful", 
"fulfill", "illustrator", "torpid", "pidgin", "gins", "instal", 
"talc", "alcove", "overtakes", "kestrel", "relabel", "beleaguered", 
"redraw", "rawhide", "identical", "caliber", "beret", "retrace", 
"acetylene", "enemas", "massacred", "redeploys", "oyster", 
"terminator", "tortillas", "last", "astronomical", "calliope", 
"operator", "tort", "orthographic", "hiccups", "upstart", 
"artificer", "cervical", "callus", "lustre", "trend", "endeavor", 
"vortex", "textures", "researcher", "heroins", "instill", "illegal", 
"galloped", "pedagogical", "callipered", "rediscover", "vertebra", 
"brasher", "herbicides", "descry", "cryptogram", "ramrod", "rodeo", 
"deodorizer", "zeros", "rosebush", "ushered", "redden", "denatures", 
"reset", "setups", "upside", "ides", "describes", "besides", 
"desperado", "adores", "reshuffle", "flea", "leaflet", "lethal", 
"halibut", "but", "button", "tonic", "niche", "cherubim", "bimbos", 
"bosun", "sunk", "unkind", "indentures", "resend", "endures", 
"restorer", "reran", "rang", "anger", "germicide", "ideological", 
"calabash", "ashamed", "medical", "caloric", "rickshas", "hasten", 
"tendon", "donkey", "keyword", "ordains", "insecticides", "desires", 
"resin", "sins", "inspector", "torrid", "rid", "rides", "despot", 
"potpie", "piebald", "aldermen", "menace", "ace", "acerbic", "bicep", 
"cephalic", "lichen", "hennas", "nasty", "styes", "yesterday", "day", 
"daybed", "bedridden", "dental", "talisman", "mankind", "indignant", 
"antique", "questionnaires", "resubmit", "mitten", "tenfold", "old", 
"olden", "denudes", "design", "ignores", "resumes", "mesdames", 
"mesas", "sass", "assemblywoman", "mangle", "glee", "leeway", 
"waylay", "laywomen", "menswear", "ear", "earldom", "domains", "ins", 
"instrumental", "tall", "all", "allegorical", "calm", "almanac", 
"nacre", "credit", "dittos", "tossup", "superman", "mandolin", 
"linesman", "manacle", "cleverer", "rerun", "runaway", "way", 
"wayfarer", "reruns", "unshaven", "ventures", "resell", "elliptical", 
"calmer", "mercuric", "ricochet", "heterodoxy", "oxymora", 
"orangutang", "angina", "inapt", "apt", "aptitudes", "descend", 
"endear", "earlobes", "bestowal", "walleyes", "yes", "yeshivas", 
"vassal", "saltcellar", "larval", "valiant", "anthropological", 
"calfskin", "kind", "inductee", "tee", "teenager", "gerund", 
"underclass", "assemblyman", "manservant", "antelopes", "peso", 
"esoteric", "rickshaw", "hawser", "servicewomen", "mental", 
"tallyhos", "hospital", "talon", "longshoremen", "men", "menthol", 
"holography", "phylum", "lumberman", "manikin", "kingpins", 
"install", "allures", "resuscitator", "tortilla", "llamas", 
"massacres", "resistor", "tormentor", "torque", "queasy", 
"asymmetric", "ricksha", "sharped", "pedlar", "largos", "gossamer", 
"merganser", "service", "icebox", "boxer", "xerography", "physical", 
"calculator", "tortures", "resonant", "anticlimax", "maxima", "imam", 
"mammon", "monograph", "aphelia", "liaison", "sonic", "nicknamed", 
"media", "diametrical", "calliper", "performed", "medulla", "llama", 
"amalgam", "gamins", "insulin", "lineman", "mantra", "transplant", 
"antigen", "genres", "respires", "resold", "oldie", "diesel", 
"seldom", "domed", "medieval", "valor", "lordship", "hipper", "per", 
"perspires", "restores", "restructures", "resort", "orthodoxy", 
"oxygen", "gentlemen", "menopausal", "saltpetre", "treacle", 
"cleaver", "verdigris", "risen", "send", "end", "endemic", 
"microfiche", "checkout", "outclass", "assault", "ultraviolet", 
"let", "letterbox", "boxcar", "carom", "roman", "manifesto", 
"stovepipes", "pesticides", "described", "bedsides", "descant", 
"anthem", "hempen", "penguins", "insignificant", "antebellum", 
"lumbar", "barracudas", "dash", "ashcan", "cannonball", "allover", 
"verbena", "enamor", "morgue", "guerrillas", "lash", "ashen", 
"henchman", "mandolins", "inspires", "resistant", "antechamber", 
"bereave", "aver", "vermin", "minim", "nimbus", "bus", "businessman", 
"mantras", "rasp", "asphalt", "altogether", "her", "hereabout", 
"outcast", "astrological", "calisthenic", "nicknames", "mescal", 
"calliopes", "pesetas", "tassel", "selectman", "mannikin", 
"kinswoman", "man", "manic", "nicer", "cerebra", "bravado", "adobe", 
"obeisant", "antiparticle", "clever", "versus", "sushi", "shirr", 
"irrelevant", "antelope", "open", "pentagon", "gonad", "nadir", 
"directorship", "hippopotami", "amid", "midwifed", "fedoras", 
"rasher", "herbal", "ball", "allot", "lot", "lotus", "tussle", 
"sledgehammer", "merchant", "ant", "antidepressant", "anther", 
"heraldry", "drywall", "allegros", "rosebud", "budgerigar", 
"garbageman", "manikins", "inscribes", "bestow", "townsmen", "menu", 
"enures", "restaurant", "antithetical", "calico", "icon", "confound", 
"underbid", "bidden", "denser", "seraphic", "hiccuped", "pedigree", 
"reeve", "ever", "vertical", "caliper", "perusal", "salami", "amir", 
"mires", "restraint", "interstellar", "larkspur", "puritanical", 
"calligrapher", "herdsman", "manatee", "teepee", "peeve", "everyday", 
"daydreamer", "meres", "result", "ultimatum", "tumbril", "rill", 
"illogical", "calligraphy", "physic", "sickbed", "bedsores", 
"resolver", "vertebras", "rascal", "call", "allergenic", "nickname", 
"amebas", "baste", "stepson", "son", "sonnet", "net", "nether", 
"heros", "rosins", "insular", "larvas", "vast", "astrakhan", 
"handyman", "manicures", "resins", "instep", "tepid", "pidgins", 
"inscribed", "bedbug", "bug", "bugbear", "earwax", "waxen", 
"xenophobia", "biathlon", "longhair", "airstrip", "ripple", "pleas", 
"eastbound", "underachiever", "verbatim", "timbre", "brew", 
"rewound", "underplay", "laywoman", "mandarins", "insofar", "farm", 
"armpit", "pitcher", "herald", "alderman", "mangos", "gossip", 
"sipped", "pedagogue", "guerillas", "laser", "serape", "aped", 
"pederast", "astound", "underground", "underpins", "insane", 
"anemic", "micra", "crane", "anew", "new", "newscast", "astir", 
"tiro", "ironware", "are", "areas", "east", "astronomic", 
"microchip", "hippopotamus", "mustache", "chervil", "villas", "lass", 
"assassin", "sinew", "newsman", "mangrove", "overtax", "taxicab", 
"cabana", "anathemas", "mast", "astronaut", "author", "horoscope", 
"opera", "eraser", "serfdom", "dominos", "nostrum", "rumpus", "pus", 
"pushcart", "arthropod", "podia", "diatom", "tomboy", "boycott", 
"ottoman", "manhunt", "untidy", "idyllic", "licensee", "seethe", 
"thereabout", "outplay", "layoff", "officer", "cerebrum", "rum", 
"rumple", "plethora", "oracle", "clergyman", "maneuver", "verandas", 
"dashikis", "kisser", "serum", "rumor", "morbid", "bidet", "detach", 
"achiever", "vertex", "text", "extremer", "merino", "inopportune", 
"uneaten", "tensor", "sort", "orthopedic", "dickie", "kielbasas", 
"sashay", "hayloft", "often", "ten", "tenpin", "pinkeye", "eyeball", 
"allegro", "grout", "outfox", "fox", "foxtrot", "rot", "rotund", 
"underwear", "earshot", "hot", "hotshot", "hotel", "telex", 
"lexicon", "congresswoman", "manor", "northbound", "undertow", 
"township", "hippos", "possessor", "sorbet", "betcha", "chart", 
"art", "article", "clear", "earwig", "wigwam", "wampum", "pummel", 
"melodic", "dictum", "tumbrel", "relic", "licit", "citadel", "delay", 
"lay", "laypeople", "plectra", "traumas", "mascot", "cotyledon", 
"donor", "nor", "normal", "malt", "altar", "tart", "artiste", 
"stencil", "cilantro", "trouper", "pericardia", "diadem", "democrat", 
"rattan", "tang", "angstrom", "romper", "perturb", "urban", "bang", 
"angel", "gelatin", "tint", "intros", "rostra", "trapper", 
"persimmon", "monsignori", "origin", "ginkgos", "gospel", "pelvis", 
"visor", "sorghum", "humid", "midair", "air", "airfoil", "oil", 
"oilskin", "kin", "kindergarten", "tentacle", "cleanser", "sermon", 
"monolog", "logarithmic", "microbes", "bestir", "tiros", "rosin", 
"sin", "singleton", "tonsil", "silicon", "con", "constraint", 
"intagli", "glint", "interwove", "overshadow", "downtrodden", 
"dentin", "tin", "tinsel", "sellout", "out", "output", "put", 
"putsch", "schoolmarm", "arm", "armor", "moribund", "underpin", 
"pint", "interloper", "periwig", "wig", "wigwag", "wagon", 
"gonorrhea", "hearten", "tenon", "nonverbal", "balsam", "samovar", 
"varmint", "interviewee", "weeper", "perturbed", "bed", "bedpan", 
"panache", "chestnut", "nut", "nutmeg", "meg", "megalopolis", 
"lissom", "somersault", "ultra", "tram", "ramp", "amputee", "teeth", 
"ethos", "hos", "hostel", "telescopic", "picayune", "uneven", 
"vendor", "dorsal", "salad", "ladybug", "bugaboo", "boomerang", 
"angora", "orangutan", "tandem", "demagogry", "gryphon", 
"honeycombed", "bedlam", "lamb", "ambergris", "risky", "sky", 
"skycap", "capstan", "tannin", "ninepin", "pinpoint", "interpret", 
"retiree", "reefer", "fer", "ferret", "returnee", "needlepoint", 
"interurban", "bantam", "tamp", "ampul", "pullout", "outrun", 
"runabout", "outstrip", "rip", "ripen", "pennon", "nonfat", "fathom", 
"homespun", "puns", "unsubscribes", "besom", "sombre", "breathe", 
"theatre", "tremor", "mortar", "tarpaulin", "lintel", "telethon", 
"honeydew", "dewlap", "lap", "lapel", "pelvic", "victim", "timpani", 
"animus", "muscat", "cat", "catsup", "sup", "superstar", "taro", 
"arousal", "salamis", "misprint", "interwoven", "venom", "nomad", 
"madam", "dam", "dampen", "penicillin", "lint", "intercom", 
"compound", "underpay", "pay", "payoff", "off", "offal", "fallout", 
"outwit", "withal", "halt", "altho", "tho", "thou", "housebound", 
"undergrad", "radio", "diocesan", "sanserif", "riffraff", 
"affidavit", "vitamin", "minicam", "campus", "pussycat", "catamaran", 
"rancor", "cornucopia", "piano", "anon", "non", "nonpartisan", 
"sandbar", "bar", "barren", "renewal", "walkout", "outruns", 
"unsnap", "naphtha", "thalamus", "musky", "skydove", "overrun", 
"run", "runs", "unsheathe", "the", "theorem", "remove", "overreach", 
"ache", "cherub", "rubes", "beseech", "echo", "chosen", "sensor", 
"sorrel", "relay", "layman", "mantillas", "lasagna", "gnat", 
"natures", "resonator", "torus", "russet", "set", "setback", 
"acknowledgement", "entanglement", "entombment", "entourages", 
"gestates", "testing", "ingratiate", "ate", "ateliers", "ersatzes", 
"zest"}

Python, 90

deducibles invertidos arrendatario arrendado casado matrimonios deducidos cesarianos bendiciones respondedores sésamo mallas vacilación ionización de ionosfera ionizador cero erosión oda odas terminaciones de desertor en tierra Minerales residen tic idealistas cosquillas canción de la canción incrustaciones continuas inculcar congregarse ilegalmente ingerir extraños gestos respuestas sésamo enmendar endivias vestuario entusiasta inquietante inquietantemente entusiasta inquietantemente inquietante inquietantemente inquietante inquietante inquietantemente inquieto inquietantemente inquieto y nervioso reconoce gestos erupciones uretrales vacilantes anticlimax maxima imagina embriaguez probada tediosamente astucia esencias cesáreas respuesta hombres lobo chaleco estimado entrometido lechuga tortilla cesión ionización ionización ingestión ionosferas rescates señalización rescate propiedad hippie piedad hippie etimólogo isthmuses sesiones inicio asentado libros contables

Primero limpio la lista manualmente eliminando todos

• palabras con mayúscula
• palabras con apóstrofe
• palabras con éêèáâàö
• Palabras de 1 y 2 letras

esto me cuesta como máximo 2 puntos porque esas palabras solo pueden estar al principio o al final de la cadena, pero reduce la lista de palabras en 1/3 y no tengo que lidiar con unicode.

Luego construyo una lista de todos los pre y sufijos, encuentro la superposición y descarto todas las palabras a menos que tanto el pre como el sufijo estén en el conjunto de superposición. Nuevamente, esto reduce a lo sumo 2 puntos de mi puntaje máximo alcanzable, pero reduce la lista de palabras a un tercio del tamaño original (intente ejecutar su algoritmo en short_list para una posible aceleración) y las palabras restantes están altamente conectadas (excepto algunas 3 -cartas de palabras que están conectadas solo entre sí). De hecho, se puede llegar a casi cualquier palabra desde cualquier otra palabra a través de una ruta con un promedio de 4 bordes.

Almaceno el número de enlaces en una matriz de adyacencia que simplifica todas las operaciones y me permite hacer cosas interesantes como mirar pasos adelante o contar ciclos ... al menos en teoría, ya que toma alrededor de 15 segundos cuadrar la matriz que realmente no hago. esto durante la búsqueda. En cambio, comienzo con un prefijo aleatorio y camino al azar, ya sea eligiendo un final uniformemente, favoreciendo los que ocurren con frecuencia (como '-ing') o los que ocurren con menos frecuencia.
Las tres variantes apestan por igual y producen cadenas en un rango de 20-40, pero al menos es rápido. Supongo que debo agregar la recursión después de todo.

from numpy import *
f = open('words_short.txt')
words = f.read().split() # 62896
f.close()

prefix = [w[:3] for w in words]     # 2292
suffix = [w[-3:] for w in words]    # 2262
common = set(prefix) & set(suffix)  # 1265

PSW = [(p,s,w) for (p,s,w) in zip(prefix, suffix, words) if p in common and s in common] # 28673
common = list(common)
mapping = dict(zip(common, range(len(common)))) # enumerate trigrams

M = zeros((len(common), len(common)), dtype=int) # for fast processing
W = [[[] for i in range(len(common))] for j in range(len(common))] # for reconstruction
for p,s,w in PSW: # build adjacency matrix
    M[mapping[p], mapping[s]] += 1
    W[mapping[p]][mapping[s]].append(w)

def chain(A, rho=0):
    B = array(A)
    links = []
    start = random.randint(len(B))
    links.append(start)
    while 1:
        nextpos = where(B[links[-1],:]>0)[0]
        if len(nextpos)==0: return links
        nextnum = B[links[-1],nextpos]

        p = ones(len(nextnum))/len(nextnum) # pick uniformly
        if rho>0: p = nextnum*1./sum(nextnum) # prioritize many links
        if rho>1: p = 1/p; p = p/sum(p) # prioritize few links

        chosen = random.choice(nextpos, p=p)
        B[links[-1], chosen] -= 1
        links.append(chosen)

def chain2words(L):
    # can only be used once because of .pop()
    z = zip(L[:-1],L[1:])
    res = []
    for p,s in z:
        res.append(W[p][s].pop())
    return res

chains = [chain(M) for i in range(100)]
bestchain = chains[argmax(map(len, chains))]
print ' '.join(chain2words(bestchain))

Originalmente quería probar algo similar a esto pero como se trata de un gráfico dirigido con ciclos, ninguno de los algoritmos estándar para la Clasificación topológica, la ruta más larga, la ruta euleriana más grande o el problema del cartero chino funciona sin grandes modificaciones.

Y solo porque se ve bien, aquí hay una imagen de la matriz de adyacencia M, M ^ 2 y M ^ infinito (infinito = 32, no cambia después) con entradas blancas = distintas de cero