2016-day02: moving within the bounds of some 2D shape

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
+}