feat(2024): add day 9 part 1

Author: believer

go/2024/README.md

@@ -22,21 +22,23 @@ Collect stars by solving puzzles. Two puzzles will be made available on each day
 | [Day 6: Guard Gallivant](https://github.com/believer/advent-of-code/blob/master/go/2024/puzzles/day06/main.go)       | 🌟  |          4778 | 🌟  |            1618 |
 | [Day 7: Bridge Repair](https://github.com/believer/advent-of-code/blob/master/go/2024/puzzles/day07/main.go)         | 🌟  | 1399219271639 | 🌟  | 275791737999003 |
 | [Day 8: Resonant Collinearity](https://github.com/believer/advent-of-code/blob/master/go/2024/puzzles/day08/main.go) | 🌟  |           220 | 🌟  |             813 |
+| [Day 9: Disk Fragmenter](https://github.com/believer/advent-of-code/blob/master/go/2024/puzzles/day09/main.go)       | 🌟  | 6384282079460 |     |                 |
 
 ## Benchmarks
 
 Using Go's built-in benchmarking with the [testing](https://pkg.go.dev/testing#hdr-Benchmarks) package. Computer is a 2021 MacBook Pro M1 Pro, 32 GB RAM.
 
-| Day |             #1 |               #2 | Improvement\*       |
-| --- | -------------: | ---------------: | ------------------- |
-| 1   |   116264 ns/op |     131233 ns/op | `3.53%` / `68.43%`  |
-| 2   |   310935 ns/op |     723512 ns/op |                     |
-| 3   |   336448 ns/op |     785320 ns/op | - / `36.98%`        |
-| 4   |   523315 ns/op |     217584 ns/op | `81.73%` / `26.09%` |
-| 5   |   778880 ns/op |    3129873 ns/op | `53.34%` / `81.91%` |
-| 6   |   312461 ns/op | 1153391125 ns/op |                     |
-| 7   | 16480300 ns/op |  842853000 ns/op | `87.01%` / `91.67%` |
-| 8   |    58749 ns/op |     121247 ns/op |                     |
+| Day |              #1 |               #2 | Improvement\*       |
+| --- | --------------: | ---------------: | ------------------- |
+| 1   |    116264 ns/op |     131233 ns/op | `3.53%` / `68.43%`  |
+| 2   |    310935 ns/op |     723512 ns/op |                     |
+| 3   |    336448 ns/op |     785320 ns/op | - / `36.98%`        |
+| 4   |    523315 ns/op |     217584 ns/op | `81.73%` / `26.09%` |
+| 5   |    778880 ns/op |    3129873 ns/op | `53.34%` / `81.91%` |
+| 6   |    312461 ns/op | 1153391125 ns/op |                     |
+| 7   |  16480300 ns/op |  842853000 ns/op | `87.01%` / `91.67%` |
+| 8   |     58749 ns/op |     121247 ns/op |                     |
+| 9   | 381476181 ns/op |                  |                     |
 
 \* compared to first solution
 

go/2024/puzzles/day09/main.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"fmt"
+	"slices"
+	"strconv"
+	"strings"
+
+	"github.com/believer/aoc-2024/utils"
+	"github.com/believer/aoc-2024/utils/files"
+)
+
+func main() {
+	fmt.Println("Part 1: ", part1("input.txt"))
+	fmt.Println("Part 2: ", part2("input.txt"))
+}
+
+func part1(name string) int {
+	line := strings.TrimSpace(files.Read(name))
+	blocked := []string{}
+	fileId := 0
+	fileBlocks := 0
+
+	// Build files and free space
+	for i, digit := range strings.Split(line, "") {
+		digitAsInt := utils.MustIntFromString(digit)
+
+		for range digitAsInt {
+			if i%2 == 0 {
+				blocked = append(blocked, strconv.Itoa(fileId))
+				fileBlocks += 1
+			} else {
+				blocked = append(blocked, ".")
+			}
+		}
+
+		if i%2 == 0 {
+			fileId++
+		}
+	}
+
+	// Compact file system
+	for i := 1; i < len(blocked); i++ {
+		rune := blocked[len(blocked)-i]
+
+		if rune == "." {
+			continue
+		}
+
+		firstEmpty := slices.Index(blocked, ".")
+
+		// The blocks have been compacted
+		if firstEmpty == fileBlocks {
+			break
+		}
+
+		blocked[firstEmpty] = rune
+		blocked[len(blocked)-i] = "."
+	}
+
+	// Calculate checksum
+	checksum := 0
+
+	for i, rune := range blocked {
+		if rune == "." {
+			break
+		}
+
+		digit := utils.MustIntFromString(string(rune))
+
+		checksum += i * digit
+	}
+
+	return checksum
+}
+
+func part2(name string) int {
+	return 0
+}

go/2024/puzzles/day09/main_test.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPart1(t *testing.T) {
+	t.Run("Part 1", func(t *testing.T) {
+		expected := 1928
+		actual := part1("test-input.txt")
+		assert.Equal(t, expected, actual)
+	})
+}
+
+func TestPart2(t *testing.T) {
+	t.Run("Part 2", func(t *testing.T) {
+		expected := 0
+		actual := part2("test-input.txt")
+		assert.Equal(t, expected, actual)
+	})
+}
+
+func BenchmarkPart1(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		part1("input.txt")
+	}
+}
+
+func BenchmarkPart2(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		part2("input.txt")
+	}
+}

go/2024/puzzles/day09/test-input.txt

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