2024:15 ⭐️⭐

Took a little bit to do first part, took a very long time to do part 2 Turned out there was a nasty bug hiding in line 134 which lead to moving of walls when surrounded by boxes. Phew.

Author: mfloryan

2024/15/day15.js

@@ -0,0 +1,265 @@
+const fs = require('fs')
+const path = require('path')
+const { off } = require('process')
+
+let input = fs.readFileSync(path.join(__dirname, 'input.txt'), { encoding: 'utf8' })
+
+function parseMapIntoList(input) {
+ return input
+ .split('\n')
+ .flatMap(
+ (l, row) => l.split('')
+ .map((c, col) => { return { c: c, x: col, y: row } }))
+}
+
+function printMap(map, move = '@') {
+ let dim = map.reduce((p, c) => [
+ Math.min(p[0], c.x),
+ Math.max(p[1], c.x),
+ Math.min(p[2], c.y),
+ Math.max(p[3], c.y)], [Infinity, -Infinity, Infinity, -Infinity])
+
+ let mapLines = []
+ for (let y = dim[2]; y <= dim[3]; y++) {
+ let line = []
+ for (let x = dim[0]; x <= dim[1]; x++) {
+ let point = map.find(p => p.x == x && p.y == y)
+ if (point) {
+ line.push(point.c == '@' ? move : point.c)
+ } else {
+ line.push('.')
+ }
+ }
+ mapLines.push(line.join(''))
+ }
+ console.log(mapLines.join('\n'))
+}
+
+
+const directions = {
+ '>': { x: 1, y: 0 },
+ '<': { x: -1, y: 0 },
+ 'v': { x: 0, y: 1 },
+ '^': { x: 0, y: -1 },
+}
+
+function executeMoves(map, moves) {
+ let robot = map.find(p => p.c == '@')
+ for (const move of moves) {
+ let offset = directions[move]
+ let newPosition = { x: robot.x + offset.x, y: robot.y + offset.y }
+ let newPositionPoint = map.find(p => p.x == newPosition.x && p.y == newPosition.y)
+ if (!newPositionPoint) {
+ robot.x = newPosition.x
+ robot.y = newPosition.y
+ } else if (newPositionPoint.c == '#') {
+ continue
+ } else if (newPositionPoint.c == 'O') {
+ let boxes = [newPositionPoint]
+ let lookAhead
+ do {
+ let lookAheadPos = { x: robot.x + offset.x * (boxes.length + 1), y: robot.y + offset.y * (boxes.length + 1) }
+ lookAhead = map.find(p => p.x == lookAheadPos.x && p.y == lookAheadPos.y)
+ if (!lookAhead || lookAhead.c != 'O') {
+ break
+ }
+ boxes.push(lookAhead)
+ } while (true)
+ if (!lookAhead) {
+ for (const box of boxes) {
+ box.x += offset.x
+ box.y += offset.y
+ }
+ robot.x += offset.x
+ robot.y += offset.y
+ }
+ } else {
+ throw "Confused"
+ }
+ }
+
+ return robot
+}
+
+function executeMoves2(map, moves) {
+ let robot = map.find(p => p.c == '@')
+ for (const move of moves) {
+ let offset = directions[move]
+ let newPosition = { x: robot.x + offset.x, y: robot.y + offset.y }
+ let newPositionPoint = map.find(p => p.x == newPosition.x && p.y == newPosition.y)
+ if (!newPositionPoint) {
+ robot.x = newPosition.x
+ robot.y = newPosition.y
+ } else if (newPositionPoint.c == '#') {
+ continue
+ } else if (newPositionPoint.c == '[' || newPositionPoint.c == ']') {
+ let boxes = []
+ if (newPositionPoint.c == '[') {
+ boxes.push(newPositionPoint, map.find(p => p.x == newPositionPoint.x + 1 && p.y == newPositionPoint.y && p.c == ']'))
+ } else {
+ boxes.push(newPositionPoint, map.find(p => p.x == newPositionPoint.x - 1 && p.y == newPositionPoint.y && p.c == '['))
+ }
+
+ if (move == '<' || move == '>') {
+
+ let lookAhead
+ do {
+ let lookAheadPos = { x: robot.x + offset.x * (boxes.length + 1), y: robot.y + offset.y * (boxes.length + 1) }
+ lookAhead = map.find(p => p.x == lookAheadPos.x && p.y == lookAheadPos.y)
+ if (!lookAhead || (lookAhead.c != '[' && lookAhead.c != ']')) {
+ break
+ }
+ boxes.push(lookAhead)
+ } while (true)
+
+ if (!lookAhead) {
+ for (const box of boxes) {
+ box.x += offset.x
+ box.y += offset.y
+ }
+ robot.x += offset.x
+ robot.y += offset.y
+ }
+
+ } else {
+ // GOIN UP or DOWN and have to find boxes in a different way
+
+ let line = newPosition.y
+ let lookAhead
+ do {
+ let lookAheadPosList = boxes.filter(b => b && b.y == line)
+ line += offset.y
+ lookAhead = lookAheadPosList.map(b => map.find(p => p.x == b.x && p.y == line))
+ //has only empty space or no parts of boxes
+ if (lookAhead.every(p => !p) || lookAhead.some(p => p && p.c == '#')) {
+ break
+ }
+ // add all boxes
+ let newLookAhead = []
+
+ for (const point of lookAhead) {
+ // add missing parts for boxes
+ newLookAhead.push(point)
+ if (point) {
+ if (point.c == '[') {
+ if (!lookAhead.find(p => p && p.x == point.x + 1 && p.c == ']')) {
+ let boxPart = map.find(p => point.y == p.y && p.x == point.x + 1 && p.c == ']')
+ if (!boxPart) throw `Missing box part for ${point}`
+ newLookAhead.push(boxPart)
+ }
+ } else if (point.c == ']') {
+ if (!lookAhead.find(p => p && p.x == point.x - 1 && p.c == '[')) {
+ let boxPart = map.find(p => point.y == p.y && p.x == point.x - 1 && p.c == '[')
+ if (!boxPart) throw `Missing box part for ${point}`
+ newLookAhead.push(boxPart)
+ }
+ }
+ }
+ }
+
+ boxes.push(...newLookAhead)
+ } while (true)
+
+ if (lookAhead.every(p => !p)) {
+ for (const box of boxes) {
+ if (box) {
+ box.x += offset.x
+ box.y += offset.y
+ }
+ }
+ robot.x += offset.x
+ robot.y += offset.y
+ }
+
+ }
+ } else {
+ console.log(newPositionPoint)
+ throw "Confused"
+ }
+ }
+}
+
+function evaluateGPS(map, point = 'O') {
+ return map.filter(p => p.c == point).reduce((p, c) => p + (c.x + 100 * c.y), 0)
+}
+
+// input = `#######
+// #...#.#
+// #.....#
+// #...O.#
+// #..O..#
+// #..OO@#
+// #..O..#
+// #.....#
+// #######
+
+// <vv<<^^<<^^`
+
+// input = `##########
+// #..O..O.O#
+// #......O.#
+// #.OO..O.O#
+// #..O@..O.#
+// #O#..O...#
+// #O..O..O.#
+// #.OO.O.OO#
+// #....O...#
+// ##########
+
+// <vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^
+// vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v
+// ><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<
+// <<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^
+// ^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><
+// ^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^
+// >^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^
+// <><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>
+// ^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>
+// v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^`
+
+// input = `
+// ########################
+// ##..............@.....##
+// ##..##....[]...[].....##
+// ##[]...........[].[]..##
+// ##..####[]..[][][][]..##
+// ##....[][]..[]....[]..##
+// ######........##[][]..##
+// ##............[][][]..##
+// ##..[][][][]......[]..##
+// ##....................##
+// ########################
+
+// vvv
+// `
+
+let [mapInput, movesInput] = input.split('\n\n')
+
+let map = parseMapIntoList(mapInput).filter(p => p.c != '.')
+let moves = movesInput.split('\n').flatMap(l => l.split(''))
+
+executeMoves(map, moves)
+
+console.log(
+ evaluateGPS(map)
+)
+
+let expansion = {
+ '#': ['#', '#'],
+ '.': ['.', '.'],
+ 'O': ['[', ']'],
+ '@': ['@', '.']
+}
+
+let newMapInput = mapInput
+ .split('\n')
+ .map(line => line.split('').flatMap(x => expansion[x]).join(''))
+ .join('\n')
+
+let map2 = parseMapIntoList(newMapInput).filter(p => p.c != '.')
+
+executeMoves2(map2, moves)
+
+console.log(
+ evaluateGPS(map2, '[')
+)