11.py

#########################################################################################################################################
# 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 = """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"""

l = grid.split('\n')
l = [e.split(' ') for e in l]
l = [list(map(int, e)) for e in l]

## prepares the grid for traversal

def max_4prod(l):
    prod = 1
    for i in range(4):
        prod *= l[i]
    fe = 0
    max_prod = prod
    for i in range(4, 19):
        try:
            new_prod = prod * l[i] / l[fe]
        except ZeroDivisionError:
            new_prod = 1
            for j in range(i - 3, i + 1):
                new_prod *= l[j]
        fe = i - 3
        prod = new_prod
        if prod > max_prod:
            max_prod = prod
    return max_prod

lv = []
for i in range(20):
    ilv = []
    for j in range(20):
        ilv.append(l[j][i])
    lv.append(ilv)

## list of all verticals

lld = []
for i in range(20):
    illd = []
    for j in range(i + 1):
        k = i - j
        illd.append(l[k][j])
    lld.append(illd)

for i in range(1, 20):
    illd = []
    for j in range(19, i - 1, -1):
        k = 19 + i - j
        illd.append(l[j][k])
    lld.append(illd)
    
## list of all left diagnols

lrd = []
for i in range(20):
    ilrd = []
    for j in range(i + 1):
        k = 19 - i + j 
        ilrd.append(l[j][k])
    lrd.append(ilrd)

for i in range(18, -1, -1):
    ilrd = []
    for j in range(i + 1):
        k = 19 - i + j 
        ilrd.append(l[k][j])
    lrd.append(ilrd)

## list of all right diagnols

for e in lld:
    while len(e) < 20:
        e.append(1)

for e in lrd:
    while len(e) < 20:
        e.append(1)

## appends 1 to lrd and lvd so they can be put into max_4prod()

max_prod = 0

for e in l + lv + lld + lrd:
    prod = max_4prod(e)
    if prod > max_prod:
        max_prod = prod

print(max_prod)