John Lekberg


JUNTO Practice - "Project Euler Problem 11"

Discussed on 2018-10-16.

Project Euler Problem 11


Solution - John

import itertools

import numpy as np

grid_str = """
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
"""

grid = np.fromiter(grid_str.split(), dtype=np.uint64)
grid.shape = 20, 20


def candidates():
    global grid

    for (r, c) in itertools.product(range(20), repeat=2):
        can_vertical = r <= 16
        can_horizontal = c <= 16

        if can_horizontal:
            yield grid[r, c : c + 4]

        if can_vertical:
            yield grid[r : r + 4, c]

        if can_horizontal and can_vertical:
            sub_grid = grid[r : r + 4, c : c + 4]
            yield np.diagonal(sub_grid)
            yield np.diagonal(np.fliplr(sub_grid))


solution = max(np.prod(c) for c in candidates())

print(solution)

Solution - Oscar

import numpy as np

with open("p11.txt") as gridfl:
    grid = gridfl.readlines()

for i, row in enumerate(grid):
    grid[i] = row.replace("\n", "").split(" ")


def best_quad():
    temp_max = 0
    max_val = 0
    for index in range(0, 17):
        temp_max = (
            g_arr[0:20, index : (index + 4)].prod(axis=1).max()
        )
        if max_val < temp_max:
            max_val = temp_max
        temp_max = (
            g_arr[index : (index + 4), 0:20].prod(axis=0).max()
        )
        if max_val < temp_max:
            max_val = temp_max
    rdiag = 1
    for row in range(0, 17):
        for column in range(0, 17):
            if max_val < rdiag:
                max_val = rdiag
            rdiag = 1
            for shift in range(0, 4):
                rdiag *= g_arr[row + shift, column + shift]
    ldiag = 1
    for row in range(19, 2, -1):
        for column in range(0, 17):
            if max_val < ldiag:
                max_val = ldiag
            ldiag = 1
            for shift in range(0, 4):
                ldiag *= g_arr[row - shift, column + shift]

    return max_val


print(best_quad())