Discussion on: AoC Day 1: Chronal Calibration

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So excited about this 🙌🏻!

Python

Part 1

data = open('input.txt', 'r')
total = 0
for line in data:
    total += int(line)
print(total)

Part 2

data = [int(i) for i in open('input.txt', 'r')]

def get_first_duplicate_total(data):
    total = 0
    prev_totals = set([0])
    while True:
        for i in data:
            total += i
            if total in prev_totals:
                return total
            prev_totals.add(total)
    return total

print(get_first_duplicate_total(data))

I also learned about itertools.cycle through reading the Reddit solutions, that would make it so that I don't need the while True:

Florian Rohrer • Dec 1 '18 • Edited

I'd also suggest to use a context manager (the with keyword) for clean opening and closing of files.

Part 1:

with open("input.txt") as f:
    freq = sum(int(i.strip()) for i in f)
freq

Part 2:

from itertools import cycle

with open("input.txt") as f:
    freqs = [int(i.strip()) for i in f]

seen = set()
current = 0
for f in cycle(freqs):
    if current in seen:
        print(current)
        break
    else:
        seen.add(current)
        current += f

Also: "Hey checkout my Github Repo!"

Ali Spittel • Dec 1 '18

True! Always forget to do that since I really only do file handling for code challenges at this point.

Ryan Palo • Dec 1 '18

Ah! So good. The clean-ness of Python never stops making me happy!

Using a set was a good idea. I didn't think of that, but it would be a lot faster for checking whether or not an item was present.

I'm going to offer unsolicited suggestions, but feel free to totally ignore them if you already knew about them (probable) or don't like them, since your solution already looks really nice.

For part one, generator expressions could be your friend:

data = open('input.txt', 'r')
total = sum(int(line) for line in data)
print(total)

For the second part, check out itertools.cycle.

Ali Spittel • Dec 1 '18

Awesome! Yes, thank you! Found out about itertools.cycle this morning -- feels super niche but still really cool.

Part one could also be a one-liner!

print(sum(int(line for line in open('input.txt', 'r'))))