Game of Life

main.py

import random 
def print_grid(grid):
    for row in grid:
        for cell in row:
            print "*  " if cell else "   ",
        print "\n"

def valid(grid, i, j):
    return i >= 0 and i < len(grid) and j >= 0 and j < len(grid[0])

def count_adjacent(grid, i, j):
    c = 0
    for a in range(-1, 2):
        for b in range(-1, 2):
            if not(b == 0 and a == 0) and valid(grid, i+a, j+b):
                c += grid[i+a][j+b]
    return c

def step(grid):
    new_grid = []
    for i in range(len(grid)):
        new = []
        for j in range(len(grid[i])):
            count = count_adjacent(grid, i, j)
            if count == 3 or (grid[i][j] and count == 2):
                new.append(1)
            else:
                new.append(0)

        new_grid.append(new)

    return new_grid


def play_game():
    grid = []
    for i in range(20):
        new = []
        for j in range(20):
            new.append(0)
        grid.append(new)
    while True:
        print_grid(grid)
        raw_input()
        grid = step(grid)


if __name__ == "__main__": play_game()