Solved first day

go.mod

@@ -0,0 +1,3 @@
+module git.gulaschkanister.de/julian.dnr/AoC-2025
+
+go 1.25.5

src/days/benchmark_test.go

@@ -0,0 +1,46 @@
+package days
+
+import (
+	"os"
+	"path"
+	"runtime"
+	"testing"
+)
+
+func init() {
+	// Changing into root dir of project
+	_, filename, _, _ := runtime.Caller(0)
+	dir := path.Join(path.Dir(filename), "..", "..")
+	err := os.Chdir(dir)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func BenchmarkDays(b *testing.B) {
+	benchmarks := []struct {
+		name     string
+		lfn      func() []string
+		fn       func([]string) int
+		expected int
+	}{
+		{"Day 1", Load_Day_1, Day01, 1150},
+	}
+
+	for _, bm := range benchmarks {
+		// Loading data for the current day
+		data := bm.lfn()
+
+		// Just for good measures
+		b.ResetTimer()
+
+		b.Run(bm.name, func(b *testing.B) {
+			for b.Loop() {
+				res := bm.fn(data)
+				if res != bm.expected {
+					b.Fatalf("invalid result: got %d, want %d", res, bm.expected)
+				}
+			}
+		})
+	}
+}

src/days/day_1.go

@@ -0,0 +1,72 @@
+package days
+
+import (
+	"bufio"
+	"log"
+	"os"
+	"strconv"
+)
+
+// numbers from 0 to 99 in order
+// instructions contain order to turn L(eft) or R(ight)
+// instructions contain the distance to turn
+// left reduces the number
+// right increases the number
+//
+// L => 76
+// R => 82
+//
+// dial starts at 50 by default
+//
+// examples:
+// 11 -> R8 => 19 -> L19 => 0
+
+func Load_Day_1() []string {
+	var lines []string
+
+	file, err := os.Open("inputs/day_1.txt")
+	if err != nil {
+		log.Fatalf("failed to open file: %s", err)
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		lines = append(lines, line)
+	}
+
+	return lines
+}
+
+func wrap(n int) int {
+	min := 0
+	max := 99
+	rangeSize := max - min + 1
+
+	return ((n-min)%rangeSize+rangeSize)%rangeSize + min
+}
+
+func Day01(instructions []string) int {
+	c := 0
+	position := 50
+	for _, i := range instructions {
+		len, err := strconv.Atoi(i[1:])
+		if err != nil {
+			log.Fatalf("failed to convert string to int: %s", err.Error())
+		}
+
+		if i[0] == 76 {
+			position = wrap(position - len)
+		} else {
+			position = wrap(position + len)
+		}
+
+		if position == 0 {
+			c++
+		}
+	}
+
+	return c
+}

src/main.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+
+	"git.gulaschkanister.de/julian.dnr/AoC-2025/src/days"
+)
+
+func main() {
+	data := days.Load_Day_1()
+
+	res := days.Day01(data)
+
+	fmt.Println(res)
+}