2024 day 9

src/2024/9/index.ts

@@ -0,0 +1,164 @@
+import { RunParams, Solution } from 'utils/dataTypes/index.js'
+import { getInput } from 'utils/files/index.js'
+import { printAnswers } from 'utils/printing/index.js'
+
+enum ItemType {
+  data,
+  space,
+}
+
+interface MapInfo {
+  id: number
+  type: ItemType
+  size: number
+  originalSize?: number
+}
+
+interface DiskLayout {
+  data: MapInfo[]
+  spaces: MapInfo[]
+}
+
+const diskMapToLayout = (diskMap: number[]): DiskLayout => {
+  const processingMap = new Map<number, MapInfo>()
+
+  let idCounter = 0
+  for (const [index, mapItem] of diskMap.entries()) {
+    const itemType: ItemType = index % 2
+
+    processingMap.set(index, {
+      id: itemType === ItemType.data ? idCounter++ : -1,
+      type: itemType,
+      size: mapItem,
+    })
+  }
+
+  const dataInfo: MapInfo[] = []
+  const spaceInfo: MapInfo[] = []
+
+  processingMap.forEach((info: MapInfo) => (info.type === ItemType.data ? dataInfo.push(info) : spaceInfo.push(info)))
+
+  return {
+    data: dataInfo,
+    spaces: spaceInfo,
+  }
+}
+
+const reorderBlocks = (diskMap: number[]): number[] => {
+  const layout = diskMapToLayout(diskMap)
+
+  let reorderedBlocks: number[] = []
+
+  for (let index = 0; index < layout.data.length; ++index) {
+    const data = layout.data[index]
+    const spaces = layout.spaces[index]
+
+    let blocks: number[] = []
+
+    if (data.size === 0) {
+      break
+    }
+
+    if (data !== undefined) {
+      blocks = Array<number>(data.size).fill(data.id)
+    }
+
+    let numSpaces = spaces?.size ?? 0
+    while (numSpaces > 0) {
+      const replacementIndex = layout.data.findLastIndex((item: MapInfo) => item.size > 0)
+
+      let replacement: MapInfo | undefined
+      if (replacementIndex > index) {
+        replacement = layout.data[replacementIndex]
+      }
+
+      if (replacement === undefined) {
+        break
+      }
+
+      const numReplacements = numSpaces > replacement.size ? replacement.size : numSpaces
+
+      blocks = [...blocks, ...Array<number>(numReplacements).fill(replacement.id)]
+
+      numSpaces -= numReplacements
+      replacement.size -= numReplacements
+    }
+
+    reorderedBlocks = [...reorderedBlocks, ...blocks]
+  }
+
+  return reorderedBlocks
+}
+
+const reorderFiles = (diskMap: number[]): number[] => {
+  const layout = diskMapToLayout(diskMap)
+
+  let reorderedFiles: number[] = []
+
+  for (let index = 0; index < layout.data.length; ++index) {
+    const data = layout.data[index]
+    const spaces = layout.spaces[index]
+
+    let files: number[] = []
+    let numSpaces = spaces?.size ?? 0
+
+    if (data !== undefined) {
+      if (data.size > 0) {
+        files = Array<number>(data.size).fill(data.id)
+      } else {
+        files = Array<number>(data.originalSize ?? 0).fill(-1)
+      }
+    }
+
+    while (numSpaces > 0) {
+      const replacementIndex = layout.data.findLastIndex((item: MapInfo) => item.size > 0 && item.size <= numSpaces)
+
+      let replacement: MapInfo | undefined
+      if (replacementIndex > index) {
+        replacement = layout.data[replacementIndex]
+      }
+
+      if (replacement === undefined) {
+        break
+      }
+
+      files = [...files, ...Array<number>(replacement.size).fill(replacement.id)]
+
+      numSpaces -= replacement.size
+      replacement.originalSize = replacement.size
+      replacement.size = 0
+    }
+
+    if (numSpaces > 0) {
+      files = [...files, ...Array<number>(numSpaces).fill(-1)]
+    }
+
+    reorderedFiles = [...reorderedFiles, ...files]
+  }
+
+  return reorderedFiles
+}
+
+const calculateChecksum = (diskData: number[]): number => {
+  return diskData.map((block: number, index: number) => index * (block < 0 ? 0 : block)).reduce((total: number, current: number) => (total += current), 0)
+}
+
+export const run = async (params: RunParams) => {
+  const solution: Solution = {
+    part1: params.isTest ? 1928 : 6310675819476,
+    part2: params.isTest ? 2858 : 6335972980679,
+  }
+
+  const inputString = await getInput(params)
+  const inputArray = inputString.split('').map(Number)
+
+  const reorderedBlocks = reorderBlocks(inputArray)
+  const reorderedFiles = reorderFiles(inputArray)
+
+  printAnswers({
+    params,
+    answer1: calculateChecksum(reorderedBlocks),
+    answer2: calculateChecksum(reorderedFiles),
+    solution,
+  })
+}