Advent of Code 2025 Day 6

— Day 6: Trash Compactor —

Can we help the cephalopod with their math homework?

Solve the problems on the math worksheet. What is the grand total found by adding together all of the answers to the individual problems?

import math

with open('data-2025-06.txt', 'r') as f:
    inp = f.read().splitlines()

mth = [i.split() for i in inp]

nums = [[int(j) for j in m] for m in mth[:4]]

ops = mth[4]

This seems reasonable simple, and in fact I did it in a google sheet on the train to start with.

summer = 0

for a,b,c,d,f in zip(nums[0], nums[1], nums[2], nums[3], ops): 
    # a, b, c, d, f
    if f == '+': 
        summer += a + b + c + d
    else: 
        summer += a * b * c * d

summer

# 6417439773370

6417439773370

— Part Two —

Actually, the problem is different. (Classic advent of code). The numbers are right to left in columns.

Solve the problems on the math worksheet again. What is the grand total found by adding together all of the answers to the individual problems?

mth = [list(i) for i in inp[:4]]

ops = inp[4].split()

summer = 0
upto = -1
zz = []

for r in range(len(mth[0])-1, -2, -1):
    # loop backwards and collect numbers as we go
    this = mth[0][r] + mth[1][r] + mth[2][r] + mth[3][r]
    if this == '    ' or r == -1:
        # we have reached a gap, do the math
        # zz
        if ops[upto] == '+': 
            summer += sum(zz)
        else: 
            summer += math.prod(zz)
        zz = []
        upto -= 1
    else: 
        # add this to the list
        zz.append(int(this.strip()))


summer

# 11043422779703 too low
# 11044319475191 manually working out with the last set
# make sure we include the last set by going to -2 
# then doing the math

11044319475191