2024 Day 9 Complete!

2024/day09/main.go

@@ -0,0 +1,258 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"sort"
+
+	helpers "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := helpers.StdinToString()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(inp string) {
+	fs := decompress(inp)
+	fs.Fragment()
+	fmt.Println("# Part 1")
+	fmt.Println(fs.Checksum())
+}
+
+func part2(inp string) {
+	fs := decompress(inp)
+	fs.SortFilesDesc()
+	fmt.Println("# Part 2")
+	for i := range fs.Files {
+		fmt.Print(fs.Files[i])
+	}
+	fmt.Println()
+	fs.Defrag()
+	fmt.Println(fs)
+	fmt.Println(fs.Checksum())
+}
+
+type Filesystem struct {
+	Files  []*FSFile
+	Blocks []*FSBlock
+}
+
+func (fs *Filesystem) SortFilesDesc() {
+	sort.Slice(fs.Files, func(i, j int) bool { return fs.Files[i].ID > fs.Files[j].ID })
+}
+
+func (fs *Filesystem) Checksum() int {
+	var ret int
+	for i := range fs.Blocks {
+		if fs.Blocks[i].ID != -1 {
+			ret = ret + (fs.Blocks[i].ID * i)
+		}
+	}
+	return ret
+}
+
+func (fs *Filesystem) Defrag() bool {
+	for i := range fs.Files {
+		fl := fs.Files[i]
+		loc := fs.FindFile(fl)
+		mv := fs.FindFirstSpaceWithSize(fl.Size())
+		if mv != -1 && mv < loc {
+			fs.MoveFile(fl, mv)
+		}
+	}
+	return false
+}
+
+func (fs *Filesystem) FindFile(fl *FSFile) int {
+	if len(fl.Blocks) <= 0 {
+		return -1
+	}
+	return fs.FindBlock(fl.Blocks[0])
+}
+
+func (fs *Filesystem) FindBlock(bl *FSBlock) int {
+	for i := range fs.Blocks {
+		if fs.Blocks[i] == bl {
+			return i
+		}
+	}
+	return -1
+}
+
+func (fs *Filesystem) MoveFile(fl *FSFile, to int) error {
+	if fs.CalcSpaceAt(to) < fl.Size() {
+		return errors.New("not enough space to move file")
+	}
+	for i := 0; i < fl.Size(); i++ {
+		fs.MoveBlock(fl.Blocks[i], to+i)
+	}
+	return nil
+}
+
+func (fs *Filesystem) MoveBlock(bl *FSBlock, to int) {
+	for i := range fs.Blocks {
+		if fs.Blocks[i] == bl {
+			// Swap i with to
+			fs.SwapBlocks(i, to)
+			return
+		}
+	}
+}
+
+func (fs *Filesystem) SwapBlocks(bl1, bl2 int) {
+	fs.Blocks[bl1], fs.Blocks[bl2] = fs.Blocks[bl2], fs.Blocks[bl1]
+}
+
+func (fs *Filesystem) FindFirstSpaceWithSize(size int) int {
+	for i := 0; i < len(fs.Blocks); i++ {
+		if fs.CalcSpaceAt(i) >= size {
+			return i
+		}
+	}
+	return -1
+}
+
+func (fs *Filesystem) CalcFileSize(id int) int {
+	startIdx, endIdx := -1, -1
+	for i := range fs.Blocks {
+		if fs.Blocks[i].ID == id && startIdx == -1 {
+			// Found it
+			startIdx = i
+		} else if fs.Blocks[i].ID != id && startIdx != -1 {
+			endIdx = i
+			return endIdx - startIdx
+		}
+	}
+	// Couldn't find the file
+	return -1
+}
+
+func (fs *Filesystem) CalcSpaceAt(idx int) int {
+	if fs.Blocks[idx].ID != -1 {
+		return 0
+	}
+	var startIdx, endIdx int
+	for i := idx; i >= 0; i-- {
+		if fs.Blocks[i].ID == -1 {
+			startIdx = i
+		} else {
+			break
+		}
+	}
+	for i := idx; i < len(fs.Blocks); i++ {
+		if fs.Blocks[i].ID == -1 {
+			endIdx = i
+		} else {
+			break
+		}
+	}
+	return (endIdx - startIdx) + 1
+}
+
+func (fs *Filesystem) Fragment() bool {
+	// Find the last block
+	lastBlock, firstSpace := fs.FindLastBlock(), fs.FindFirstSpace()
+	if firstSpace < lastBlock {
+		// Swap these two
+		fs.SwapBlocks(firstSpace, lastBlock)
+		// Recurse
+		return fs.Fragment()
+	} else {
+		return true
+	}
+}
+
+func (fs *Filesystem) FindLastBlock() int {
+	for i := len(fs.Blocks) - 1; i >= 0; i-- {
+		if fs.Blocks[i].ID != -1 {
+			return i
+		}
+	}
+	return -1
+}
+
+func (fs *Filesystem) FindFirstSpace() int {
+	// Now find the first space
+	for i := 0; i < len(fs.Blocks); i++ {
+		if fs.Blocks[i].ID == -1 {
+			return i
+		}
+	}
+	return -1
+}
+
+func (fs *Filesystem) AddFile(id, size int) {
+	fl := &FSFile{ID: id}
+	for i := 0; i < size; i++ {
+		c := &FSBlock{ID: id}
+		fl.Blocks = append(fl.Blocks, c)
+		fs.Blocks = append(fs.Blocks, c)
+	}
+	fs.Files = append(fs.Files, fl)
+}
+
+func (fs *Filesystem) AddSpace(size int) {
+	for i := 0; i < size; i++ {
+		c := &FSBlock{ID: -1}
+		fs.Blocks = append(fs.Blocks, c)
+	}
+}
+
+func (fs Filesystem) String() string {
+	var ret string
+	for i := range fs.Blocks {
+		ret = fmt.Sprintf("%s%s", ret, fs.Blocks[i])
+	}
+	return ret
+}
+
+type FSFile struct {
+	ID     int
+	Blocks []*FSBlock
+}
+
+func (f *FSFile) Size() int {
+	return len(f.Blocks)
+}
+
+func (f FSFile) String() string {
+	return fmt.Sprintf("[%d;%d]", f.ID, f.Size())
+}
+
+type FSBlock struct {
+	ID int
+}
+
+func (fsc FSBlock) String() string {
+	if fsc.ID == -1 {
+		return "[.]"
+	}
+	return fmt.Sprintf("[%d]", fsc.ID)
+}
+
+func decompress(inp string) Filesystem {
+	ret := Filesystem{}
+	latestId := 0
+	file := true
+	for i := range inp {
+		size := int(inp[i] - '0')
+		if file {
+			ret.AddFile(latestId, size)
+			latestId = latestId + 1
+		} else {
+			ret.AddSpace(size)
+		}
+		file = !file
+	}
+	return ret
+}
+
+func add(out []byte, v byte, count int) []byte {
+	for i := 0; i < count; i++ {
+		out = append(out, v)
+	}
+	return out
+}

2024/day09/testinput

@@ -0,0 +1 @@
+2333133121414131402

go.mod

@@ -1,6 +1,6 @@
 module git.bullercodeworks.com/brian/adventofcode
 
-go 1.23
+go 1.23.0
 
 require (
 	github.com/br0xen/termbox-screen v0.0.0-20190712162752-c91f70ac38c6