ProjectEuler/problem-0011.py at master · p13lgst/ProjectEuler · GitHub

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"""
Problem 11 - Largest product in a grid

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

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

What is the greatest product of four adjacent numbers in the same direction
(up, down, left, right, or diagonally) in the 20×20 grid?

Note: The grid is in the file 11.txt4
"""


def parse_grid(lines):
    grid = []
    for line in lines:
        row = []
        for i in line.rstrip('\n').split():
            row.append(int(i))
        grid.append(row)
    return grid


grid = parse_grid(open('11.txt').readlines())
greatest = 0

# HORIZONTAL
for i in range(len(grid)):
    for j in range(len(grid) - 3):
        n = grid[i][j] * grid[i][j+1] * grid[i][j+2] * grid[i][j+3]
        if n > greatest:
            greatest = n

# VERTICAL
for i in range(len(grid) - 3):
    for j in range(len(grid)):
        n = grid[i][j] * grid[i+1][j] * grid[i+2][j] * grid[i+3][j]
        if n > greatest:
            greatest = n

# DIAGONAL from T-L to B-R
for i in range(len(grid) - 3):
    for j in range(len(grid) - 3):
        n = grid[i][j] * grid[i+1][j+1] * grid[i+2][j+2] * grid[i+3][j+3]
        if n > greatest:
            greatest = n

# DIAGONAL from T-R to B-L
for i in range(len(grid) - 3):
    for j in range(3, len(grid)):
        n = grid[i][j] * grid[i+1][j-1] * grid[i+2][j-2] * grid[i+3][j-3]
        if n > greatest:
            greatest = n

print(greatest)