day2

d2/d2.go

@@ -0,0 +1,42 @@
+package d2
+
+import (
+	"log"
+	"strconv"
+	"strings"
+)
+
+type position struct {
+	x int64
+	y int64
+}
+
+func D2(input string) int64 {
+	position := position{}
+	directions := strings.Split(strings.TrimSpace(input), "\n")
+
+	for _, direction := range directions {
+		directionAndValue := strings.Split(strings.TrimSpace(direction), " ")
+
+		if len(directionAndValue) != 2 {
+			log.Fatal("line has wrong number of elements: ", direction)
+		}
+
+		value, err := strconv.Atoi(directionAndValue[1])
+
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		switch directionAndValue[0] {
+		case "forward":
+			position.x += int64(value)
+		case "down":
+			position.y += int64(value)
+		case "up":
+			position.y -= int64(value)
+		}
+	}
+
+	return position.x * position.y
+}

d2/d2_test.go

@@ -0,0 +1,20 @@
+package d2
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestD2(t *testing.T) {
+
+	input := `
+forward 5
+down 5
+forward 8
+up 3
+down 8
+forward 2`
+
+	assert.EqualValues(t, 150, D2(input))
+}

main.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/fotonmoton/aoc2021/client"
 	"github.com/fotonmoton/aoc2021/d1"
+	"github.com/fotonmoton/aoc2021/d2"
 )
 
 func main() {
@@ -18,4 +19,5 @@ func main() {
 	client := client.NewClient(strings.TrimSpace(session))
 
 	fmt.Printf("day1: %v\n", d1.D1(string(client.Day(1))))
+	fmt.Printf("day2: %v\n", d2.D2(string(client.Day(2))))
 }