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perk11perk11
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2024 day 9
1 parent 0d5a68d commit 2962e3c

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4 files changed

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4 files changed

+190
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‎2024/day9/day9.go

Lines changed: 87 additions & 0 deletions
Original file line numberDiff line numberDiff line change
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package main
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import (
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"fmt"
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"os"
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"strconv"
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"strings"
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)
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func main() {
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filenames := []string{"testInput", "input"}
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for _, fileName := range filenames {
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fileContents, err := os.ReadFile(fileName)
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if err != nil {
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panic(err)
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}
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fmt.Println(fileName)
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fileContentsSplit := strings.Split(string(fileContents), "")
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fileContentsInt := make([]int, len(fileContentsSplit))
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diskSize := 0
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for index, value := range fileContentsSplit {
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fileContentsInt[index], _ = strconv.Atoi(value)
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diskSize += fileContentsInt[index]
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}
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//int for file id, -1 for free space
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var fileSystemContents = make([]int, diskSize)
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var cursorIsOnFile = true
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var fileSystemPosition = 0
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var fileIndex = -1
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for _, value := range fileContentsInt {
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if cursorIsOnFile {
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fileIndex++
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}
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nextFileStart := fileSystemPosition + value
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for ; fileSystemPosition < nextFileStart; fileSystemPosition++ {
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if cursorIsOnFile {
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fileSystemContents[fileSystemPosition] = fileIndex
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} else {
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fileSystemContents[fileSystemPosition] = -1 //free space
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}
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}
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cursorIsOnFile = !cursorIsOnFile
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}
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lastFreeSpaceInTheStart := 0
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firstNonFreeSpaceInTheEnd := len(fileSystemContents) - 1
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for {
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lastFreeSpaceInTheStart, firstNonFreeSpaceInTheEnd = defragOneBlock(lastFreeSpaceInTheStart, firstNonFreeSpaceInTheEnd, &fileSystemContents)
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if lastFreeSpaceInTheStart == -1 || firstNonFreeSpaceInTheEnd == -1 {
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break
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}
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}
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var total = 0
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for index, value := range fileSystemContents {
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if value != -1 {
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total += index * value
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}
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}
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println(total)
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}
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}
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func defragOneBlock(lastFreeSpaceInTheStart int, firstNonFreeSpaceInTheEnd int, diskContents *[]int) (int, int) {
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var blockToMove = -1
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var freeSpace = -1
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for index := firstNonFreeSpaceInTheEnd; index > lastFreeSpaceInTheStart; index-- {
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if (*diskContents)[index] == -1 {
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continue
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}
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blockToMove = index
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break
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}
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for index := lastFreeSpaceInTheStart; index < firstNonFreeSpaceInTheEnd; index++ {
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if (*diskContents)[index] != -1 {
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continue
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}
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freeSpace = index
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break
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}
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if blockToMove == -1 || freeSpace == -1 {
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return -1, -1
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}
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(*diskContents)[freeSpace] = (*diskContents)[blockToMove]
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(*diskContents)[blockToMove] = -1
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return freeSpace, blockToMove
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}

‎2024/day9/day9_pt2.go

Lines changed: 101 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,101 @@
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package main
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import (
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"fmt"
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"os"
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"strconv"
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"strings"
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)
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func main() {
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filenames := []string{"testInput", "input"}
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for _, fileName := range filenames {
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fileContents, err := os.ReadFile(fileName)
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if err != nil {
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panic(err)
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}
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fmt.Println(fileName)
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fileContentsSplit := strings.Split(string(fileContents), "")
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fileContentsInt := make([]int, len(fileContentsSplit))
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diskSize := 0
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for index, value := range fileContentsSplit {
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fileContentsInt[index], _ = strconv.Atoi(value)
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diskSize += fileContentsInt[index]
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}
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//int for file id, -1 for free space
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var fileSystemContents = make([]int, diskSize)
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var cursorIsOnFile = true
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var fileSystemPosition = 0
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var fileIndex = -1
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var fileSizes = make([]int, len(fileContents)/2+1)
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for _, value := range fileContentsInt {
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if cursorIsOnFile {
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fileIndex++
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fileSizes[fileIndex] = value
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}
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nextFileStart := fileSystemPosition + value
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for ; fileSystemPosition < nextFileStart; fileSystemPosition++ {
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if cursorIsOnFile {
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fileSystemContents[fileSystemPosition] = fileIndex
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} else {
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fileSystemContents[fileSystemPosition] = -1 //free space
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}
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}
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cursorIsOnFile = !cursorIsOnFile
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}
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lastKnownFileEndPosition := len(fileSystemContents) - 1
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for {
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lastKnownFileEndPosition = defragOneFile(lastKnownFileEndPosition, &fileSystemContents, &fileSizes)
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if lastKnownFileEndPosition <= 0 {
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break
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}
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}
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var total = 0
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for index, value := range fileSystemContents {
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if value != -1 {
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total += index * value
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}
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}
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println(total)
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}
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}
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func defragOneFile(lastKnownFileEndPosition int, diskContents *[]int, fileSizes *[]int) int {
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var actualFileEnd = -1
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for index := lastKnownFileEndPosition; index > 0; index-- {
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if (*diskContents)[index] == -1 {
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continue
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}
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actualFileEnd = index
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break
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}
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if actualFileEnd == -1 {
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return -1
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}
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var fileId = (*diskContents)[actualFileEnd]
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var fileSize = (*fileSizes)[fileId]
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var freeSpaceStart = -1
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scanDiskForFreeSpace:
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for diskIndex := 0; diskIndex < len(*diskContents); diskIndex++ {
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for fileIndex := diskIndex; fileIndex < min(diskIndex+fileSize, len(*diskContents)-1); fileIndex++ {
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if (*diskContents)[fileIndex] != -1 {
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continue scanDiskForFreeSpace
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}
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}
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freeSpaceStart = diskIndex
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break
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}
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var fileStart = actualFileEnd - fileSize + 1
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if freeSpaceStart == -1 || freeSpaceStart > fileStart {
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return fileStart - 1
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}
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for index := fileStart; index <= actualFileEnd; index++ {
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(*diskContents)[index] = -1
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}
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for index := freeSpaceStart; index <= min(freeSpaceStart+fileSize-1, len(*diskContents)-1); index++ {
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(*diskContents)[index] = fileId
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}
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return fileStart - 1
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}

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