feat: completed day 1 for advent of code 2025

2025/cmd/root.go

@@ -8,9 +8,13 @@ import (
 
 	"cpatino.com/advent-of-code/2025/cmd/generate"
 	"github.com/spf13/cobra"
+
+	"cpatino.com/advent-of-code/2025/day01"
 )
 
-var days = map[int]func(string) (any, any){}
+var days = map[int]func(string) (any, any){
+	1: day01.Run,
+}
 
 var rootCmd = &cobra.Command{
 	Use:   "advent-of-code",

2025/day01/day01.go

@@ -0,0 +1,93 @@
+package day01
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+func Part1(lines []string) int {
+	pos := 50
+	count := 0
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if len(line) < 2 {
+			continue
+		}
+
+		dir := line[0]
+		var dist int
+		_, err := fmt.Sscanf(line[1:], "%d", &dist)
+		if err != nil {
+			continue
+		}
+
+		switch dir {
+		case 'L':
+			pos = (pos - dist + 100) % 100
+		case 'R':
+			pos = (pos + dist) % 100
+		}
+
+		if pos == 0 {
+			count++
+		}
+	}
+
+	return count
+}
+
+func Part2(lines []string) int {
+	pos := 50
+	count := 0
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if len(line) < 2 {
+			continue
+		}
+		dir := line[0]
+		var dist int
+		_, err := fmt.Sscanf(line[1:], "%d", &dist)
+		if err != nil {
+			continue
+		}
+		step := 0
+		if dir == 'L' {
+			step = -1
+		} else if dir == 'R' {
+			step = 1
+		}
+		for i := 0; i < dist; i++ {
+			pos = (pos + step + 100) % 100
+			if pos == 0 {
+				count++
+			}
+		}
+	}
+	return count
+}
+
+func Run(filename string) (any, any) {
+	file, err := os.Open(filename)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	var lines []string
+	for scanner.Scan() {
+		line := scanner.Text()
+		lines = append(lines, line)
+	}
+
+	if err := scanner.Err(); err != nil {
+		panic(err)
+	}
+
+	part1 := Part1(lines)
+	part2 := Part2(lines)
+
+	return part1, part2
+}

2025/day01/day01_test.go

@@ -0,0 +1,34 @@
+package day01
+
+import (
+	"os"
+	"testing"
+)
+
+type TestCase struct {
+	FileName string
+	Part1    any
+	Part2    any
+}
+
+func TestDay01(t *testing.T) {
+	tests := []TestCase{
+		{"test.txt", 3, 6},
+		{"input.txt", 1086, 6268},
+	}
+
+	for _, test := range tests {
+		if _, err := os.Stat(test.FileName); os.IsNotExist(err) {
+			t.Fatalf("test file does not exist: %v", test.FileName)
+		}
+
+		part1, part2 := Run(test.FileName)
+		if test.Part1 != nil && part1 != test.Part1 {
+			t.Fatalf("%s: unexpected part1:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part1, part1)
+		}
+
+		if test.Part2 != nil && part2 != test.Part2 {
+			t.Fatalf("%s: unexpected part2:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part2, part2)
+		}
+	}
+}

2025/day01/test.txt

@@ -0,0 +1,10 @@
+L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82