From 00369ca422fd9d0e4a23b5a2d3b51aee58e49454 Mon Sep 17 00:00:00 2001
From: alexchao26 <alexchaoo@gmail.com>
Date: Thu, 2 Dec 2021 00:23:58 -0500
Subject: [PATCH] day 2, knocking off rust still

---
 2021/day02/main.go      | 67 +++++++++++++++++++++++++++++++++++++++++
 2021/day02/main_test.go | 53 ++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+)
 create mode 100644 2021/day02/main.go
 create mode 100644 2021/day02/main_test.go

diff --git a/2021/day02/main.go b/2021/day02/main.go
new file mode 100644
index 0000000..75ef99f
--- /dev/null
+++ b/2021/day02/main.go
@@ -0,0 +1,67 @@
+package main
+
+import (
+	_ "embed"
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/cast"
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+//go:embed input.txt
+var input string
+
+func init() {
+	// do this in init (not main) so test file has same input
+	input = strings.TrimRight(input, "\n")
+	if len(input) == 0 {
+		panic("empty input.txt file")
+	}
+}
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	ans := day2(input, part)
+	util.CopyToClipboard(fmt.Sprintf("%v", ans))
+	fmt.Println("Output:", ans)
+}
+
+func day2(input string, part int) int {
+	var horiz, depth int
+	var aim int
+
+	for _, line := range strings.Split(input, "\n") {
+		parts := strings.Split(line, " ")
+		dir := parts[0]
+		dist := cast.ToInt(parts[1])
+
+		if part == 1 {
+			switch dir {
+			case "down":
+				depth += dist
+			case "up":
+				depth -= dist
+			case "forward":
+				horiz += dist
+			}
+		} else {
+			switch dir {
+			case "down":
+				aim += dist
+			case "up":
+				aim -= dist
+			case "forward":
+				horiz += dist
+				depth += aim * dist
+			}
+		}
+	}
+
+	return horiz * depth
+}
diff --git a/2021/day02/main_test.go b/2021/day02/main_test.go
new file mode 100644
index 0000000..3d0f8d2
--- /dev/null
+++ b/2021/day02/main_test.go
@@ -0,0 +1,53 @@
+package main
+
+import (
+	"testing"
+)
+
+var example = `forward 5
+down 5
+forward 8
+up 3
+down 8
+forward 2`
+
+func Test_day2(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		part  int
+		want  int
+	}{
+		{
+			name:  "example",
+			input: example,
+			part:  1,
+			want:  150,
+		},
+		{
+			name:  "actual",
+			input: input,
+			part:  1,
+			want:  1813801,
+		},
+		{
+			name:  "example",
+			input: example,
+			part:  2,
+			want:  900,
+		},
+		{
+			name:  "actual",
+			input: input,
+			part:  2,
+			want:  1960569556,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := day2(tt.input, tt.part); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}