Lista 2d en Python
ar = [[0 for j in range(m)] for i in range(n)]
Dull Dunlin
ar = [[0 for j in range(m)] for i in range(n)]
def list_2D(r, c):
l = []
for i in range(r):
x = [0] * c
l.append(x)
return l
length, breadth = x, y
matrix = [[-1 for j in range(breadth)] for i in range(length)]
# every element is -1