🐛 Account for file ids > 9

.gitignore

@@ -23,3 +23,4 @@ go.work.sum
 
 # env file
 .env
+defrag

blocks.go

@@ -1,30 +1,31 @@
 package defrag
 
 import (
-	"bytes"
 	"strconv"
-	"strings"
 )
 
-func Blocks(diskMap []byte) ([]byte, error) {
+func Blocks(diskMap []byte) ([]int, error) {
 	current := 0
 	onFile := false
-	buff := bytes.Buffer{}
+	out := []int{}
 	for _, by := range diskMap {
 		count, err := strconv.Atoi(string(by))
 		if err != nil {
 			return nil, err
 		}
 		onFile = !onFile
+
 		if count == 0 {
 			continue
 		}
-		append := "."
+		val := -1
 		if onFile {
-			append = strconv.Itoa(current)
+			val = current
 			current++
 		}
-		buff.WriteString(strings.Repeat(append, count))
+		for idx := 0; idx < count; idx++ {
+			out = append(out, val)
+		}
 	}
-	return buff.Bytes(), nil
+	return out, nil
 }

blocks_test.go

@@ -7,16 +7,15 @@ import (
 )
 
 type tt struct {
-	name      string
-	diskMap   []byte
-	blocks    []byte
-	defragged []byte
+	name    string
+	diskMap []byte
+	blocks  []int
 }
 
 func sampleTests() []tt {
 	return []tt{
-		{"short", []byte("12345"), []byte("0..111....22222"), []byte("022111222......")},
-		{"longer", []byte("2333133121414131402"), []byte("00...111...2...333.44.5555.6666.777.888899"), []byte("0099811188827773336446555566..............")},
+		{"short", []byte("12345"), []int{0, -1, -1, 1, 1, 1, -1, -1, -1, -1, 2, 2, 2, 2, 2}},
+		{"longer", []byte("2333133121414131402"), []int{0, 0, -1, -1, -1, 1, 1, 1, -1, -1, -1, 2, -1, -1, -1, 3, 3, 3, -1, 4, 4, -1, 5, 5, 5, 5, -1, 6, 6, 6, 6, -1, 7, 7, 7, -1, 8, 8, 8, 8, 9, 9}},
 	}
 }
 

checksum.go

@@ -0,0 +1,14 @@
+package defrag
+
+// import "strconv"
+
+func Checksum(blocks []int) (sum int, err error) {
+	for idx, fileByte := range blocks {
+		if fileByte == -1 {
+			break
+		}
+
+		sum += idx * fileByte
+	}
+	return
+}

cmd/defrag/main.go

@@ -29,6 +29,7 @@ func main() {
 
 	blocks, err := defrag.Blocks(input)
 	handleErr(err)
+
 	err = defrag.Defrag(blocks)
 	handleErr(err)
 
@@ -36,5 +37,11 @@ func main() {
 	fmt.Printf("%s\n", input)
 
 	fmt.Println("Got this")
-	fmt.Printf("%s\n", blocks)
+	fmt.Printf("%v\n", blocks)
+
+	sum, err := defrag.Checksum(blocks)
+	handleErr(err)
+
+	fmt.Println("Checksum:")
+	fmt.Printf("%d\n", sum)
 }

defrag.go

@@ -2,18 +2,18 @@ package defrag
 
 // Defrag performs an in-place sort of blocks.
 // If an error occurs during processing, it will be returned. The slice may have been partially sorted.
-func Defrag(blocks []byte) error {
+func Defrag(blocks []int) error {
 	lastPulled := len(blocks)
 	lastPushed := -1
 	for block := 0; block < len(blocks); block++ {
-		if blocks[block] != '.' {
+		if blocks[block] != -1 {
 			continue
 		}
 		if lastPulled <= block {
 			break
 		}
 		for swap := lastPulled - 1; swap > lastPushed; swap-- {
-			if blocks[swap] == '.' {
+			if blocks[swap] == -1 {
 				continue
 			}
 			blocks[block], blocks[swap] = blocks[swap], blocks[block]

defrag_test.go

@@ -1,19 +0,0 @@
-package defrag
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestDefrag(t *testing.T) {
-	for _, testcase := range sampleTests() {
-		t.Run(testcase.name, func(sub *testing.T) {
-			blocks := make([]byte, len(testcase.blocks))
-			copy(blocks, testcase.blocks)
-			err := Defrag(blocks)
-			require.NoError(sub, err)
-			require.Equal(sub, testcase.defragged, blocks)
-		})
-	}
-}