The below code is a solution I put together for the Project Euler #11 question which asked to find the largest product of 4 numbers of any direction in a matrix (horiz, vertic, and diag all acceptable.)
Coding methodology: To me this is the most important. Is the algorithm I used feasible or mostly correct, if not how do I correct it and why won't it work or scale? I realize in some cases there are always going to be optimal solutions that will be over my head mathematically, but generally you can yield a solution that is within a reasonable range of optimal that is passable without knowing a ton of number theory in my experience. Where possible, I hope to learn algorithms along the way (such as the Sieve of Eratosthenes for prime ranges).
Coding execution: Given some pseudocode that we determine algorithmically will work, is the code written executed without redundancies and minimizing runtime. As you can see below, my coding is terrible and I'm sure violates many of the principles here.
Being more pythonic: Is something I'm not doing pythonic or can it be done simpler with some sort of library I don't know about. I believe this is mostly semantic though in some cases can have large effects on performance (for instance using
map()
instead of afor
loop to applyint()
).After looking through another submitted solution on Code Review, I saw that:
lines = [s for s in b.splitlines()] bb = [] i = 0 for line in lines: bb.append(map(int,lines[i].split())) i += 1
can simplify to:
bb = [map(int, row.split()) for row in open('number.txt').read().splitlines()]
b = """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"""
lines = [s for s in b.splitlines()]
bb = []
i = 0
for line in lines:
bb.append(map(int,lines[i].split()))
i += 1
n = 4
count = []
row_ct = 0
for row in bb:
column_ct = 0
for column in row:
#each case is checking if it's possible to perform the multiplication from left to right
#horizontal
if len(bb) - column_ct >= n:
count.append(bb[row_ct][column_ct]*
bb[row_ct][column_ct+1]*
bb[row_ct][column_ct+2]*
bb[row_ct][column_ct+3])
#vertical
if len(bb) - row_ct >= n:
count.append(bb[row_ct][column_ct]*
bb[row_ct+1][column_ct]*
bb[row_ct+2][column_ct]*
bb[row_ct+3][column_ct])
#downleft
if column_ct >= n and len(bb) - row_ct >= n:
count.append(bb[row_ct][column_ct]*
bb[row_ct+1][column_ct-1]*
bb[row_ct+2][column_ct-2]*
bb[row_ct+3][column_ct-3])
#downright
if column_ct <= len(bb) - n and len(bb) - row_ct >= n:
count.append(bb[row_ct][column_ct]*
bb[row_ct+1][column_ct+1]*
bb[row_ct+2][column_ct+2]*
bb[row_ct+3][column_ct+3])
#column and row_ct are indexes so ie. at third point column_ct will be 3, row count will be
# 0, used for condition checking
column_ct += 1
row_ct += 1
max(count)