From c5a976fd9c7e40d70ad375a501dbf657a98979ab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorben=20G=C3=BCnther?= <admin@xenrox.net>
Date: Sun, 5 Dec 2021 00:23:24 +0100
Subject: [PATCH] Solve day 2 part 2

---
 day02/day02_test.go | 11 +++++++++++
 day02/main.go       | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/day02/day02_test.go b/day02/day02_test.go
index 009ab8c..3528e6c 100644
--- a/day02/day02_test.go
+++ b/day02/day02_test.go
@@ -12,3 +12,14 @@ func Test1(t *testing.T) {
 		t.Errorf("wrong result, expected %d, got %d", 150, res)
 	}
 }
+
+func Test2(t *testing.T) {
+	res, err := calc2("../data/day02_test.dat")
+	if err != nil {
+		t.Errorf("error calculating: %v", err)
+	}
+
+	if res != 900 {
+		t.Errorf("wrong result, expected %d, got %d", 150, res)
+	}
+}
diff --git a/day02/main.go b/day02/main.go
index 6a2eadf..ec32804 100644
--- a/day02/main.go
+++ b/day02/main.go
@@ -14,6 +14,13 @@ func Run() {
 	}
 
 	fmt.Printf("Part 1: %d\n", res)
+
+	res, err = calc2("data/day02.dat")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Part 2: %d\n", res)
 }
 
 func calc1(path string) (int, error) {
@@ -43,3 +50,32 @@ func calc1(path string) (int, error) {
 
 	return depth * hor, nil
 }
+
+func calc2(path string) (int, error) {
+	lines, err := readFile(path)
+	if err != nil {
+		return 0, err
+	}
+
+	var hor, depth, aim int
+	for i := 0; i < len(lines); i++ {
+		v, err := strconv.Atoi(lines[i][1])
+		if err != nil {
+			return 0, err
+		}
+
+		switch lines[i][0] {
+		case "forward":
+			hor += v
+			depth += aim * v
+		case "down":
+			aim += v
+		case "up":
+			aim -= v
+		default:
+			return 0, errors.New("illegal direction command")
+		}
+	}
+
+	return depth * hor, nil
+}
-- 
2.44.0