day17

day17/day.go

@@ -0,0 +1,74 @@
+package day17
+
+import (
+	"crypto/md5"
+	"fmt"
+	"math"
+	"tools"
+)
+
+func getMD5Sum(s string) string {
+	return fmt.Sprintf("%x", md5.Sum([]byte(s)))
+}
+
+type DirDelta struct {
+	x int
+	y int
+}
+
+var dirDeltas = []DirDelta{{0, -1}, {0, 1}, {-1, 0}, {1, 0}}
+var dirs = []string{"U", "D", "L", "R"}
+var pathLen = math.MaxInt32
+var foundPath = ""
+
+func findPath(passcode, path string, x, y int, findLongest bool) {
+	doors := getMD5Sum(passcode + path)[:4]
+	if !findLongest && len(path) >= pathLen {
+		return
+	}
+	if x == 3 && y == 3 {
+		if findLongest {
+			if len(path) > pathLen {
+				foundPath = path
+				pathLen = len(path)
+			}
+		} else {
+			if len(path) < pathLen {
+				foundPath = path
+				pathLen = len(path)
+			}
+		}
+		return
+	}
+
+	for i, c := range doors {
+		if x+dirDeltas[i].x < 0 || x+dirDeltas[i].x > 3 || y+dirDeltas[i].y < 0 || y+dirDeltas[i].y > 3 {
+			// border case
+			continue
+		}
+
+		if c > 97 { // door open
+			findPath(passcode, path+dirs[i], x+dirDeltas[i].x, y+dirDeltas[i].y, findLongest)
+		}
+	}
+}
+
+func Part1(puzzle tools.AoCPuzzle) interface{} {
+	for _, passcode := range puzzle.GetInputArray() {
+		pathLen = math.MaxInt32
+		findPath(passcode, "", 0, 0, false)
+		// fmt.Println("Passcode:", passcode, "Path:", foundPath)
+	}
+
+	return foundPath
+}
+
+func Part2(puzzle tools.AoCPuzzle) interface{} {
+	for _, passcode := range puzzle.GetInputArray() {
+		pathLen = 0
+		findPath(passcode, "", 0, 0, true)
+		// fmt.Println("Passcode:", passcode, "Len:", len(foundPath), "Path:", foundPath)
+	}
+
+	return len(foundPath)
+}

inputs/17

@@ -0,0 +1 @@
+pvhmgsws

inputs/17_test

@@ -0,0 +1,3 @@
+ihgpwlah
+kglvqrro
+ulqzkmiv

main.go

@@ -16,6 +16,7 @@ import (
 	"aoc2016/day14"
 	"aoc2016/day15"
 	"aoc2016/day16"
+	"aoc2016/day17"
 	"flag"
 	"fmt"
 	"os"
@@ -49,7 +50,7 @@ func initDayFunctions() {
 		14: {1: day14.Part1, 2: day14.Part2},
 		15: {1: day15.Part1, 2: day15.Part2},
 		16: {1: day16.Part1, 2: day16.Part2},
-		//		17: {1: day17.Part1, 2: day17.Part2},
+		17: {1: day17.Part1, 2: day17.Part2},
 		//		18: {1: day18.Part1, 2: day18.Part2},
 		//		19: {1: day19.Part1, 2: day19.Part2},
 		//		20: {1: day20.Part1, 2: day20.Part2},