day9

2024/go/day09/day09.go

@@ -0,0 +1,117 @@
+package day09
+
+import (
+	"adventofcode2024/utils"
+	"fmt"
+)
+
+func Part1(input string) int {
+	disk := []int{}
+	file_id := 0
+	for i := 0; i <= len(input); i++ {
+		for x := 0; x < utils.MustAtoi(string(input[i])); x++ {
+			disk = append(disk, file_id)
+		}
+		i++
+		if i < len(input) {
+			for x := 0; x < utils.MustAtoi(string(input[i])); x++ {
+				disk = append(disk, -1)
+			}
+		}
+		file_id++
+	}
+	
+	printDisk(disk)
+
+	for i:=len(disk)-1;i>0;i--{
+		if disk[i] != -1 {
+			id := disk[i]
+			disk[i] = -1
+			for j:=0;j<=len(disk);j++ {
+				if disk[j] == -1 {
+					disk[j] = id
+					break
+				}
+			}
+		}
+	}
+	printDisk(disk)
+
+	checksum := 0
+	for i:=0;i<len(disk);i++ {
+		if disk[i] != -1 {
+			checksum += i * disk[i]
+		}
+	}
+	return checksum
+}
+
+func Part2(input string) int {
+	disk := []int{}
+	file_id := 0
+	for i := 0; i <= len(input); i++ {
+		for x := 0; x < utils.MustAtoi(string(input[i])); x++ {
+			disk = append(disk, file_id)
+		}
+		i++
+		if i < len(input) {
+			for x := 0; x < utils.MustAtoi(string(input[i])); x++ {
+				disk = append(disk, -1)
+			}
+		}
+		file_id++
+	}
+	
+	printDisk(disk)
+
+	for i:=len(disk)-1;i>0;i--{
+		size := 0
+		if disk[i] != -1 {
+			id := disk[i]
+			for {
+				if i-size > 0 && disk[i-size] == id {
+					size++
+				} else {
+					break
+				}
+			}
+			free := 0
+			j := 0
+			found := false
+			for ;j<i && free < size;j++{
+				if disk[j] != -1 { 
+					free = 0
+					continue 
+				}
+				free++
+				if free == size { found = true }
+			}
+			if found {
+				for k:=0;k<size;k++ {
+					disk[i-k] = -1
+					disk[j-size+k] = id
+				}
+//				printDisk(disk)
+			}
+			i -= (size -1)
+			
+		}
+	}
+	printDisk(disk)
+
+	checksum := 0
+	for i:=0;i<len(disk);i++ {
+		if disk[i] != -1 {
+			checksum += i * disk[i]
+		}
+	}
+	return checksum}
+
+func printDisk(disk []int) {
+	for _, x := range disk {
+		if x == -1 {fmt.Print(".")} else {
+			fmt.Printf("%d", x)
+		}
+	}
+	fmt.Print("\n")
+}

2024/go/day09/day09_test.go

@@ -0,0 +1,17 @@
+package day09
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPart1(t *testing.T) {
+	r := Part1("2333133121414131402")
+	require.Equal(t,1928, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2("2333133121414131402")
+	require.Equal(t, 2858, r)
+}