problem_011.py

# coding: utf-8

'''
In the 20×20 grid below, four numbers along a diagonal line have been marked in red.

08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 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 03 45 02 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 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48

The product of these numbers is 26 × 63 × 78 × 14 = 1788696.
'''

L = [
    [int(i) for i in "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08".split()],
    [int(i) for i in "49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00".split()],
    [int(i) for i in "81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65".split()],
    [int(i) for i in "52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91".split()],
    [int(i) for i in "22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80".split()],
    [int(i) for i in "24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50".split()],
    [int(i) for i in "32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70".split()],
    [int(i) for i in "67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21".split()],
    [int(i) for i in "24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72".split()],
    [int(i) for i in "21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95".split()],
    [int(i) for i in "78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92".split()],
    [int(i) for i in "16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57".split()],
    [int(i) for i in "86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58".split()],
    [int(i) for i in "19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40".split()],
    [int(i) for i in "04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66".split()],
    [int(i) for i in "88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69".split()],
    [int(i) for i in "04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36".split()],
    [int(i) for i in "20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16".split()],
    [int(i) for i in "20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54".split()],
    [int(i) for i in "01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48".split()],
]


def main():
    # 20 rows of 20 integers
    _max = 0

    for i in range(20):
        for j in range(16):
            # horizontal products
            product = L[i][j] * L[i][j + 1] * L[i][j + 2] * L[i][j + 3]
            if product > _max:
                _max = product
            # up/down products
            product = L[j][i] * L[j + 1][i] * L[j + 2][i] * L[j + 3][i]
            if product > _max:
                _max = product

    # diagonal products left to right
    for i in range(16):
        for j in range(16):
            product = L[i][j] * L[i + 1][j + 1] * L[i + 2][j + 2] * L[i + 3][j + 3]
            if product > _max:
                _max = product

    # diagonal products right to left
    for i in range(3, 20):
        for j in range(16):
            product = L[i][j] * L[i - 1][j + 1] * L[i - 2][j + 2] * L[i - 3][j + 3]
            if product > _max:
                _max = product

    return _max


if __name__ == '__main__':
    print(main())
    # 70600674 in 578usec