day 01

01/go.mod

@@ -0,0 +1,3 @@
+module adventofcode2024/01
+
+go 1.23

01/main.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"math"
+	"os"
+	"regexp"
+	"sort"
+	"strconv"
+)
+
+var (
+	inputFile = flag.String("input", "input.txt", "input filename")
+	reLine    = regexp.MustCompile(`(?m)^(\d+)\s+(\d+)$`)
+)
+
+func main() {
+	flag.Parse()
+	input, err := os.ReadFile(*inputFile)
+	if err != nil {
+		panic(err)
+	}
+
+	var leftList, rightList []int
+	for _, match := range reLine.FindAllStringSubmatch(string(input), -1) {
+		leftNumber, err := strconv.Atoi(match[1])
+		if err != nil {
+			panic(err)
+		}
+
+		rightNumber, err := strconv.Atoi(match[2])
+		if err != nil {
+			panic(err)
+		}
+
+		leftList = append(leftList, leftNumber)
+		rightList = append(rightList, rightNumber)
+	}
+
+	sort.SliceStable(leftList, func(i, j int) bool {
+		return leftList[i] < leftList[j]
+	})
+	sort.SliceStable(rightList, func(i, j int) bool {
+		return rightList[i] < rightList[j]
+	})
+
+	totalDistance := 0
+	for i := 0; i < len(leftList); i++ {
+		totalDistance += int(math.Abs(float64(leftList[i] - rightList[i])))
+	}
+
+	fmt.Println(totalDistance)
+}