add day-09 + benchmarks

day-09/internal/one/benchmark

@@ -0,0 +1,6 @@
+goos: linux
+goarch: amd64
+pkg: github.com/onyx-and-iris/aoc2024/day-09/internal/one
+cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
+BenchmarkSolve-12    	1000000000	         0.1535 ns/op
+ok  	github.com/onyx-and-iris/aoc2024/day-09/internal/one	1.893s

day-09/internal/one/block.go

@@ -0,0 +1,8 @@
+package one
+
+const empty = -1
+
+type block struct {
+	used int
+	free int
+}

day-09/internal/one/disk.go

@@ -0,0 +1,59 @@
+package one
+
+import (
+	"fmt"
+	"slices"
+	"strings"
+)
+
+type disk struct {
+	data      []int
+	totalUsed int
+}
+
+func newDisk(blocks []block) disk {
+	var totalUsed int
+	data := []int{}
+	for id, block := range blocks {
+		for range block.used {
+			data = append(data, id)
+		}
+		for range block.free {
+			data = append(data, empty)
+		}
+		totalUsed += block.used
+	}
+
+	return disk{
+		data:      data,
+		totalUsed: totalUsed,
+	}
+}
+
+func (d *disk) len() int {
+	return d.totalUsed
+}
+
+func (d *disk) sort() {
+	for i := len(d.data) - 1; i >= 0; i-- {
+		if d.data[i] != empty {
+			indx := slices.Index(d.data, empty)
+			if indx == d.len() {
+				break
+			}
+			d.data[i], d.data[indx] = d.data[indx], d.data[i]
+		}
+	}
+}
+
+func (d *disk) debug() string {
+	var sb strings.Builder
+	for _, n := range d.data {
+		if n == empty {
+			sb.WriteRune('.')
+		} else {
+			sb.WriteString(fmt.Sprintf("%d", n))
+		}
+	}
+	return sb.String()
+}

day-09/internal/one/solve.go

@@ -0,0 +1,27 @@
+package one
+
+import (
+	"bytes"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func Solve(buf []byte) (int, error) {
+	r := bytes.NewReader(buf)
+	blocks, err := parseLines(r)
+	if err != nil {
+		return 0, err
+	}
+
+	disk := newDisk(blocks)
+	disk.sort()
+	log.Debug(disk.debug())
+
+	var i, checksum int
+	for range disk.len() {
+		checksum += i * disk.data[i]
+		i++
+	}
+
+	return checksum, nil
+}

day-09/internal/one/solve_internal_test.go

@@ -0,0 +1,15 @@
+package one
+
+import (
+	_ "embed"
+	"os"
+	"testing"
+)
+
+//go:embed testdata/input.txt
+var data []byte
+
+func BenchmarkSolve(b *testing.B) {
+	os.Stdout, _ = os.Open(os.DevNull)
+	Solve(data)
+}

day-09/internal/one/util.go

@@ -0,0 +1,38 @@
+package one
+
+import (
+	"bufio"
+	"io"
+	"strconv"
+)
+
+func parseLines(r io.Reader) ([]block, error) {
+	var blocks []block
+
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		for i := 0; i < len(line); i += 2 {
+			var free int
+			if i < len(line)-1 {
+				free = mustConv(string(line[i+1]))
+			}
+			blocks = append(blocks, block{mustConv(string(line[i])), free})
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return []block{}, err
+	}
+
+	return blocks, nil
+}
+
+func mustConv(s string) int {
+	n, err := strconv.Atoi(s)
+	if err != nil {
+		panic(err)
+	}
+	return n
+}