Discussion on: AoC Day 2: Inventory Management System

[Florian Rohrer]

Part 1

from collections import Counter

with open("input.txt") as f:
    ids = [Counter(l.strip()) for l in f]

count2 = 0
count3 = 0
for c in ids:
    if 2 in c.values(): count2 += 1
    if 3 in c.values(): count3 += 1

print(count2 * count3)

Part 2

from editdistance import eval as dist
from itertools import product

with open("input.txt") as f:
    ids = [l.strip() for l in f]

for a, b in product(ids, ids):
    d = dist(a, b)
    if d == 1:
        print(a, b)
        break

And from the output, I just copied and pasted the necessary characters that matched. That was faster than comming up with a custom method to do so.

[Ryan Palo]

Nice! Did you implement editdistance yourself, or is that an external library?

[Florian Rohrer]

It is external. I found it via a quick google search. The edit distance measures how many operations - insertion, deletion or substitution - it takes to get from one string to the other. Since all the strings in the puzzle input have the same length, insertion and deletion do not come into play and it works out perfectly.

[Ryan Palo]

Ok that’s cool, just checking. Neat!