Advent of Code 2024

Solutions for 2024

Day 1

1. Parse the input and find the difference and add them up
2. Some numbers appear in both lists, so calculate a similarity score

• Nice easy introduction for day 1
• Getting the input in the right shape was easy
• Pre-calculate part two with collections.Counter rather than counting each time

Day 2

1. Check to see if the reports are all increasing or decreasing
2. Check the reports, but with the ability to remove one value

• Make a function and loop through the input
• Use the same function, but with another function to edit possible input

Day 3

1. Find the sum of the multiply statements - but find them first
2. There’s a switch that turns the statements on and off

• Regex only on day 3. Find the mul() statements, then evaluate them
• Find the do() and don’t() statements as well, then iterate

Day 4

1. Do a word search for XMAS
2. Actually search for MAS in in X shape

• Iterate for X and then go for different directions
• Iterate for A and then go for different directions

Day 5

1. Sum up the middle value of the updates that are in the correct order
2. Sort the bad updates into the correct order and sum the middle values

• Loop through the lists and if subsequent numbers are in the correct order, the whole list is in order
• For the bad lists, place the pieces in the correct order, then sum up. More difficult than it sounds

Day 6

Day 7

Day 8

Day 9

Day 10

Day 11

Day 12

Day 13

Day 14

Day 15

Day 16

Day 17

Day 18

Day 19

Day 20

Day 21

Day 22

Day 23

Day 24

Day 25