From 3412d43ec248572f45b62b85cf69c9403517b505 Mon Sep 17 00:00:00 2001
From: alexchao26 <alexchaoo@gmail.com>
Date: Sun, 20 Dec 2020 22:57:33 -0500
Subject: [PATCH] 2016-day02: moving within the bounds of some 2D shape

---
 2016/day02/main.go      | 84 +++++++++++++++++++++++++++++++++++++++++
 2016/day02/main_test.go | 26 +++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 2016/day02/main.go
 create mode 100644 2016/day02/main_test.go

diff --git a/2016/day02/main.go b/2016/day02/main.go
new file mode 100644
index 0000000..00ce0d3
--- /dev/null
+++ b/2016/day02/main.go
@@ -0,0 +1,84 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	ans := part1(util.ReadFile("./input.txt"), part)
+	fmt.Println("Output:", ans)
+}
+
+func part1(input string, part int) string {
+	directions := parseInput(input)
+
+	var pressedButtons string
+
+	// set starting row, col and phone pad based on part number
+	// pad the borders of phonePad with spaces to make border collision logic
+	// the same in both parts
+	// used a space instead of empty string so it's easier to look at...
+	row, col := 2, 2
+	phonePad := [][]string{
+		{" ", " ", " ", " ", " "},
+		{" ", "1", "2", "3", " "},
+		{" ", "4", "5", "6", " "},
+		{" ", "7", "8", "9", " "},
+		{" ", " ", " ", " ", " "},
+	}
+	if part == 2 {
+		phonePad = [][]string{
+			{" ", " ", " ", " ", " ", " ", " "},
+			{" ", " ", " ", "1", " ", " ", " "},
+			{" ", " ", "2", "3", "4", " ", " "},
+			{" ", "5", "6", "7", "8", "9", " "},
+			{" ", " ", "A", "B", "C", " ", " "},
+			{" ", " ", " ", "D", " ", " ", " "},
+			{" ", " ", " ", " ", " ", " ", " "},
+		}
+		row, col = 3, 1
+	}
+	for _, list := range directions {
+		for _, direction := range list {
+			switch direction {
+			case "U":
+				if phonePad[row-1][col] != " " {
+					row--
+				}
+			case "D":
+				if phonePad[row+1][col] != " " {
+					row++
+				}
+			case "L":
+				if phonePad[row][col-1] != " " {
+					col--
+				}
+			case "R":
+				if phonePad[row][col+1] != " " {
+					col++
+				}
+			default:
+				panic("unhandled direction: " + direction)
+			}
+		}
+		pressedButtons += phonePad[row][col]
+	}
+
+	return pressedButtons
+}
+
+func parseInput(input string) (ans [][]string) {
+	for _, line := range strings.Split(input, "\n") {
+		ans = append(ans, strings.Split(line, ""))
+	}
+	return ans
+}
diff --git a/2016/day02/main_test.go b/2016/day02/main_test.go
new file mode 100644
index 0000000..9aec0ef
--- /dev/null
+++ b/2016/day02/main_test.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func Test_part1(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		part  int
+		want  string
+	}{
+		{"actual", util.ReadFile("input.txt"), 1, "12578"},
+		{"actual", util.ReadFile("input.txt"), 2, "516DD"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part1(tt.input, tt.part); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}