Advent of Code 2022 - Day 3: Rucksack Reorganization Solution

Part 1

Find shared item and calculate based on lowercase or uppercase

Implementation

1const fs = require("fs")
2
3const data = fs.readFileSync("./input", "utf-8").split(/\r?\n/).filter(Boolean)
4
5const isLower = char => char === char.toLowerCase()
6
7const res = data.reduce((acc, el) => {
8  const mid = Math.floor(el.length / 2)
9  const [part1, part2] = [el.substring(0, mid), el.substring(mid)]
10  const sharedItem = part1.split("").find(char => part2.includes(char))
11
12  return (
13    acc +
14    sharedItem.charCodeAt(0) -
15    (isLower(sharedItem) ? "a" : "A").charCodeAt(0) +
16    1 +
17    (isLower(sharedItem) ? 0 : 26)
18  )
19}, 0)
20
21console.log(res)

Part 2

Group data into chunks with size of 3

Calculation is the same as Part 1

Implementation

1const fs = require("fs")
2
3const data = fs.readFileSync("./input", "utf-8").split(/\r?\n/).filter(Boolean)
4
5const isLower = char => char === char.toLowerCase()
6
7const chunks = []
8const chunkSize = 3
9for (let i = 0; i < data.length; i += chunkSize) {
10  const chunk = data.slice(i, i + chunkSize)
11  chunks.push(chunk)
12}
13
14const res = chunks.reduce((acc, [part1, part2, part3]) => {
15  const sharedItem = part1
16    .split("")
17    .find(char => part2.includes(char) && part3.includes(char))
18
19  return (
20    acc +
21    sharedItem.charCodeAt(0) -
22    (isLower(sharedItem) ? "a" : "A").charCodeAt(0) +
23    1 +
24    (isLower(sharedItem) ? 0 : 26)
25  )
26}, 0)
27
28console.log(res)

References

Original problem