import random

size(600,600)

cols = 30
rows = 30

cells = [[True for x in range(cols)] for y in range(rows)]

wsq = width/cols
hsq = height/rows
noStroke()

for y in range(rows):
    for x in range(cols):
        cells[x][y] = bool(random.getrandbits(1))


for y in range(rows):
    for x in range(cols):
        if cells[x][y]:
            fill(255)
        else:
            fill(0)
        rect(x*wsq,y*hsq,width/cols,height/rows)
        
print(cells)