Project Euler Problem #11

euler11.py

'''
Project Euler Problem #11

What is the greatest product of four adjacent numbers in the same direction
(up, down, left, right, or diagonally) in the 20×20 grid?
'''
grid = (
    ( 8, 2,22,97,38,15, 0,40, 0,75, 4, 5, 7,78,52,12,50,77,91, 8),
    (49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48, 4,56,62, 0),
    (81,49,31,73,55,79,14,29,93,71,40,67,53,88,30, 3,49,13,36,65),
    (52,70,95,23, 4,60,11,42,69,24,68,56, 1,32,56,71,37, 2,36,91),
    (22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80),
    (24,47,32,60,99, 3,45, 2,44,75,33,53,78,36,84,20,35,17,12,50),
    (32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70),
    (67,26,20,68, 2,62,12,20,95,63,94,39,63, 8,40,91,66,49,94,21),
    (24,55,58, 5,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72),
    (21,36,23, 9,75, 0,76,44,20,45,35,14, 0,61,33,97,34,31,33,95),
    (78,17,53,28,22,75,31,67,15,94, 3,80, 4,62,16,14, 9,53,56,92),
    (16,39, 5,42,96,35,31,47,55,58,88,24, 0,17,54,24,36,29,85,57),
    (86,56, 0,48,35,71,89, 7, 5,44,44,37,44,60,21,58,51,54,17,58),
    (19,80,81,68, 5,94,47,69,28,73,92,13,86,52,17,77, 4,89,55,40),
    ( 4,52, 8,83,97,35,99,16, 7,97,57,32,16,26,26,79,33,27,98,66),
    (88,36,68,87,57,62,20,72, 3,46,33,67,46,55,12,32,63,93,53,69),
    ( 4,42,16,73,38,25,39,11,24,94,72,18, 8,46,29,32,40,62,76,36),
    (20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74, 4,36,16),
    (20,73,35,29,78,31,90, 1,74,31,49,71,48,86,81,16,23,57, 5,54),
    ( 1,70,54,71,83,51,54,69,16,92,33,48,61,43,52, 1,89,19,67,48))

def check_across(x, y):
    return grid[y][x] * grid[y][x+1] * grid[y][x+2] * grid[y][x+3]

def check_down(x, y):
    return grid[y][x] * grid[y+1][x] * grid[y+2][x] * grid[y+3][x]

def check_diagonal_right(x, y):
    return grid[y][x] * grid[y+1][x+1] * grid[y+2][x+2] * grid[y+3][x+3]

def check_diagonal_left(x, y):
    return grid[y][x] * grid[y+1][x-1] * grid[y+2][x-2] * grid[y+3][x-3]

if __name__ == '__main__':
    largest_product = 0
    funcs = (check_across, check_down, check_diagonal_left, check_diagonal_right)

    for y in range(len(grid) - 4):
        for x in range(len(grid[y]) - 4):
            for func in funcs:
                tmp = func(x, y)
                if tmp > largest_product: largest_product = tmp

    print('Problem 11 solution: {:,}'.format(largest_product))