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•

lf

Last test of second part tripped me up because I had 'y' incrementing by 1 each step, rather than 'dy'.
Took me bloody ages to figure that out, not as bad as not reading the bloody question yesterday though.

https://github.com/lewfowls/AoC2020/blob/main/Day3code.py

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wence in reply to @lf

Very C-like, I ended up writing

def trees(grid, r, d):
    return sum(row[(i*r) % len(row)] == "#"
               for i, row in enumerate(grid[::d]))

for the find-trees function.

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lf in reply to @wence
were you saying my function was very C-like?

i've actually just re-written it and it's almost bang on the same as yours with enumerate - had seen a few people talking about that so tried to get that working. still not entirely sure what the :: does in grid[::d], apart from take every d'th y.

my function:
```
def findTrees2(funcdata, dx, dy):
    numTrees = 0
    for i, line in enumerate(funcdata[::dy]):
        if line[(i*dx) % len(line)] == '#': numTrees += 1
    return numTrees
```
edit: was also confused as to why you can't print an enumerate object until you put it into a list. but guess that's a conversation for data structures... i should really do a bit more formal learning

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