2024 Day 08

2024/d06/index.ts

@@ -19,24 +19,24 @@ const rotate = (speed: Vec2): Vec2 => {
       x: -1,
       y: 0,
     }
-  } 
-  
+  }
+
   // From going left to going upwards
   if (speed.x === -1 && speed.y === 0) {
     return {
       x: 0,
       y: -1,
     }
-  } 
-  
+  }
+
   // From going upwards to going right
   if (speed.x === 0 && speed.y === -1) {
     return {
       x: 1,
       y: 0,
     }
-  } 
-  
+  }
+
   // From going right to going downwards
   if (speed.x === 1 && speed.y === 0) {
     return {

2024/d08/index.ts

@@ -0,0 +1,180 @@
+import { readFileSync } from 'node:fs'
+
+import { runExamples, runSolution } from '@magiczne/advent-of-code-ts-core/aoc'
+import { combinationsWithoutRepetition } from '@magiczne/advent-of-code-ts-core/combinatorics'
+import type { Vec2 } from '@magiczne/advent-of-code-ts-core/types'
+
+type Antenna = Vec2 & { type: 'Antenna'; code: string }
+type Antinode = { type: 'Antinode'; code: string }
+type MapItem = null | Antenna | Antinode
+type Map = Array<Array<MapItem>>
+
+interface Input {
+  map: Map
+  antennas: Record<string, Array<Antenna>>
+}
+
+const DEBUG = false
+const printMap = (map: Map): void => {
+  if (!DEBUG) {
+    return
+  }
+
+  map.forEach(row => {
+    let rowString = ''
+
+    row.forEach(cell => {
+      if (cell.type === 'Antenna') {
+        rowString += cell.code
+      } else if (cell.type === 'Antinode') {
+        rowString += '#'
+      } else {
+        rowString += '.'
+      }
+    })
+
+    console.log(rowString)
+  })
+
+  console.log('')
+}
+
+const part1 = (input: Input): number => {
+  const map = structuredClone(input.map)
+
+  Object.values(input.antennas).forEach(antennaSet => {
+    combinationsWithoutRepetition(antennaSet, 2).forEach(([firstNode, secondNode]) => {
+      const distanceX = Math.abs(firstNode.x - secondNode.x)
+      const distanceY = Math.abs(firstNode.y - secondNode.y)
+
+      const secondAntinodeDir: Vec2 = { x: firstNode.x < secondNode.x ? -1 : 1, y: firstNode.y < secondNode.y ? -1 : 1 }
+      const firstAntinodeDir: Vec2 = { x: firstNode.x < secondNode.x ? 1 : -1, y: firstNode.y < secondNode.y ? 1 : -1 }
+
+      const antinodes: ReadonlyArray<Vec2> = [
+        {
+          x: firstNode.x - firstAntinodeDir.x * distanceX,
+          y: firstNode.y - firstAntinodeDir.y * distanceY,
+        },
+        {
+          x: secondNode.x - secondAntinodeDir.x * distanceX,
+          y: secondNode.y - secondAntinodeDir.y * distanceY,
+        },
+      ]
+
+      antinodes.forEach(antinode => {
+        if (map[antinode.y]?.[antinode.x] !== undefined) {
+          map[antinode.y][antinode.x] = { type: 'Antinode', code: firstNode.code }
+        }
+      })
+    })
+  })
+
+  printMap(map)
+
+  return map
+    .map(row => {
+      return row.reduce((acc, item) => {
+        if (item?.type === 'Antinode') {
+          return acc + 1
+        }
+
+        return acc
+      }, 0)
+    })
+    .reduce((acc, rowCount) => acc + rowCount, 0)
+}
+
+const part2 = (input: Input): number => {
+  const map = structuredClone(input.map)
+
+  Object.values(input.antennas).forEach(antennaSet => {
+    combinationsWithoutRepetition(antennaSet, 2).forEach(([firstNode, secondNode]) => {
+      const distanceX = Math.abs(firstNode.x - secondNode.x)
+      const distanceY = Math.abs(firstNode.y - secondNode.y)
+
+      const secondAntinodeDir: Vec2 = { x: firstNode.x < secondNode.x ? -1 : 1, y: firstNode.y < secondNode.y ? -1 : 1 }
+      const firstAntinodeDir: Vec2 = { x: firstNode.x < secondNode.x ? 1 : -1, y: firstNode.y < secondNode.y ? 1 : -1 }
+
+      let antinodes: Array<Vec2> = []
+
+      // Generate antinodes in first direction
+      for (let i = 1; ; i++) {
+        const x = firstNode.x - firstAntinodeDir.x * (distanceX * i)
+        const y = firstNode.y - firstAntinodeDir.y * (distanceY * i)
+
+        if (map[y]?.[x] === undefined) {
+          break
+        }
+
+        antinodes.push({ x, y })
+      }
+
+      // Generate antinodes in second direction
+      for (let i = 1; ; i++) {
+        const x = secondNode.x - secondAntinodeDir.x * (distanceX * i)
+        const y = secondNode.y - secondAntinodeDir.y * (distanceY * i)
+
+        if (map[y]?.[x] === undefined) {
+          break
+        }
+
+        antinodes.push({ x, y })
+      }
+
+      antinodes.forEach(antinode => {
+        if (map[antinode.y]?.[antinode.x] !== undefined) {
+          map[antinode.y][antinode.x] = { type: 'Antinode', code: firstNode.code }
+        }
+      })
+    })
+  })
+
+  printMap(map)
+
+  return map
+    .map(row => {
+      return row.reduce((acc, item) => {
+        if (item !== null) {
+          return acc + 1
+        }
+
+        return acc
+      }, 0)
+    })
+    .reduce((acc, rowCount) => acc + rowCount, 0)
+}
+
+const reader = (file: string): Input => {
+  const map = readFileSync(file, 'utf-8')
+    .trim()
+    .split('\n')
+    .map((line, y) => {
+      return line.split('').map((item, x) => {
+        if (item === '.') {
+          return null
+        }
+
+        return {
+          type: 'Antenna',
+          code: item,
+          x,
+          y,
+        }
+      })
+    })
+
+  const antennas = Object.groupBy(
+    map.flatMap(row => {
+      return row.filter(item => item !== null)
+    }),
+    antenna => antenna.code,
+  )
+
+  return {
+    antennas: antennas as Record<string, Array<Antenna>>,
+    map: map as Array<Array<MapItem>>,
+  }
+}
+
+runExamples(2024, '08', reader, part1, part2)
+runSolution(2024, '08', reader, part1, part2)

2024/d08/input.txt

@@ -0,0 +1,50 @@
+..........................4..............7..q.....
+..........G..42.f......K.........7................
+D.t...S......A....................................
+..K.................................I.............
+G....D...f.tA..H.S..........o................N....
+t....f..............4..A........B.........N.....q.
+...b...k....f..h..........6.......................
+..........b....m................7...............Q.
+....h....G.2........K.i...........................
+.F...2.....D....H..6..o........I..................
+k.......b..................K......I.....e.....B...
+.............Sp..o....n....R.............N........
+F............d................2...................
+.........i........................................
+.....ma.....d......p.Q..n.....7....9..........N...
+......m..H......S...8......n.....Q...e............
+.i..............8......O.....I................c...
+..d......k....R.....................9....z........
+..p.......m......n...............P................
+.......pLb...................W..j................q
+.....C..1..........u.....c.....jO...Z..o.........V
+..C.....i........X1......9......e....j.....B....c.
+......................9...........Q..Z............
+.d....h..L...............8........O...............
+....C....r..L....R...............6................
+...........h.............1.t......P.......V.......
+.......L.1........................................
+..................................................
+X.......................................V.....W...
+rx........a.X.......0....l..........6.........z...
+..r........a.8.................................z..
+................w.........l..............P....A...
+..........E....s..w.j........l...............W....
+...v...............c..............W..y...V.O......
+.....X..g.Y...0w......l...................u.......
+.C.......Y...0....................................
+...g..UJ...0........v.............................
+.U...aY...........................................
+....5........Y....MUJ..........B..................
+.......g...5M........J.......w.........u..Z.......
+................TE................................
+..U....r....5.................J..........Z........
+.......5...3......s........T......................
+.............E.T..............................u...
+...........v........y.......................P.....
+................s.................................
+x............M3........e..........................
+........3...v......MT.............................
+.............x....................................
+....x..........3............y.....................

2024/d08/test-runs/0.txt

@@ -0,0 +1,12 @@
+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............

2024/d08/test-runs/1.txt

@@ -0,0 +1,10 @@
+T.........
+...T......
+.T........
+..........
+..........
+..........
+..........
+..........
+..........
+..........

ts-core/combinatorics/combinations-without-repetition.ts

@@ -0,0 +1,23 @@
+const combinationsWithoutRepetition = <T>(items: ReadonlyArray<T>, length: number): ReadonlyArray<ReadonlyArray<T>> => {
+  const result: Array<ReadonlyArray<T>> = []
+
+  const backtrack = (combination: Array<T>, start: number): void => {
+    if (combination.length === length) {
+      result.push([...combination])
+
+      return
+    }
+
+    for (let i = start; i < items.length; i++) {
+      combination.push(items[i])
+      backtrack(combination, i + 1)
+      combination.pop()
+    }
+  }
+
+  backtrack([], 0)
+
+  return result
+}
+
+export { combinationsWithoutRepetition }

ts-core/combinatorics/index.ts

@@ -1 +1,2 @@
 export { combinations } from './combinations'
+export { combinationsWithoutRepetition } from './combinations-without-repetition'

ts-core/types/Vec2.ts

@@ -0,0 +1,6 @@
+interface Vec2 {
+  x: number
+  y: number
+}
+
+export type { Vec2 }

ts-core/types/index.ts

@@ -0,0 +1 @@
+export type * from './Vec2'