Day 7: Bridge Repair

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

    • @TunaCowboy
      1•12 days ago

      It’s not a long lived project, it’s a puzzle, and once solved never needs to run again. My objective here is to get the correct answer, not win a style contest.

      Can you provide a link to your solution? I’d like to check it out.

      • @[email protected]English
        1•12 days ago

        My initial comment was a bit harsh, I’m sorry for that. It was meant to be a bit of a joke. Anyway here’s my code. Do note that I don’t do the challenges timed so I have a bit more time to name my variables accordingly. Takes 35 seconds to run on a pc with a AMD Ryzen 5 5600

        import sys
from tqdm import tqdm


input = sys.stdin.read()

def all_operator_permutations(operator_count):
    if operator_count == 0:
        return [[]]

    smaller_permutations = all_operator_permutations(operator_count-1)
    return [
            *[['+', *ops] for ops in smaller_permutations],
            *[['*', *ops] for ops in smaller_permutations],
            *[['||', *ops] for ops in smaller_permutations],
            ]

def test_operators(ops, values):
    res = values.pop(0)
    for op in ops:
        match op:
            case '*':
                res *= values.pop(0)
            case '+':
                res += values.pop(0)
            case '||':
                res = int(f"{res}{values.pop(0)}")
    return res


total_calibration_result = 0

for line in tqdm(input.splitlines()[:]):
    target, *tail = line.split(':')
    target = int(target)
    values = [int(val) for val in tail[0].split()]

    all_perms = all_operator_permutations(len(values) - 1)
    ops = all_perms.pop()
    while True:
        res = test_operators(ops, values.copy())
        if res == target:
            total_calibration_result += target
            break
        if not all_perms:
            break
        ops = all_perms.pop()

print(total_calibration_result)