day18: solved part two

day18/main.go

@@ -19,43 +19,63 @@ func printSpace(space [][]int) {
 	var max = len(space) - 1
 	for y := range space {
 		for x := range space[y] {
+			var val string
 			switch space[y][x] {
 			case CORRUPTED:
-				fmt.Print(" C")
+				val = "C"
 			case UNIVSITED:
-				fmt.Print(" .")
+				val = "."
 			default:
-				fmt.Printf("%2d", space[y][x])
+				val = util.Itoa(space[y][x])
 			}
 			if max > 9 {
-				fmt.Print(" ")
+				fmt.Printf("%3s ", val)
+			} else {
+				fmt.Printf("%2s", val)
 			}
 		}
 		fmt.Println()
 	}
 	fmt.Println()
 }
 
-func readSpace(space [][]int, count int) {
+func readPoints() []util.Point {
 	var scanner = bufio.NewScanner(os.Stdin)
 	var pattern = regexp.MustCompile(`^(\d+),(\d+)$`)
 
-	var fallen int
-	for scanner.Scan() && fallen < count {
+	var points = []util.Point{}
+	for scanner.Scan() {
 		var line = scanner.Text()
 		var matches = pattern.FindStringSubmatch(line)
 		var x, y int
 		if len(matches) > 0 {
 			x = util.Atoi(matches[1])
 			y = util.Atoi(matches[2])
-			space[y][x] = CORRUPTED
-			fallen++
+			points = append(points, util.Point{Y: y, X: x})
 		}
 	}
 	if err := scanner.Err(); err != nil {
 		fmt.Fprintf(os.Stderr, "Error: %s\n", err)
 		os.Exit(1)
 	}
+
+	return points
+}
+
+func resetSpace(space [][]int) {
+	for y := range space {
+		for x := range space[y] {
+			if space[y][x] > 0 {
+				space[y][x] = 0
+			}
+		}
+	}
+}
+
+func fillSpace(space [][]int, points []util.Point) {
+	for _, point := range points {
+		space[point.Y][point.X] = CORRUPTED
+	}
 }
 
 func makeSpace(size int) [][]int {
@@ -106,10 +126,20 @@ func main() {
 	var count = flag.Int("count", 1024, "number of bytes that have fallen")
 	flag.Parse()
 
+	var points = readPoints()
 	var space = makeSpace(*max)
-	readSpace(space, *count)
+	fillSpace(space, points[:*count])
 	printSpace(space)
 	var steps = searchPath(space) - 1
 	fmt.Printf("found exit in %d steps\n", steps)
 	printSpace(space)
+
+	for _, point := range points[*count:] {
+		resetSpace(space)
+		fillSpace(space, []util.Point{point})
+		if searchPath(space) == 0 {
+			fmt.Printf("no way out at coordinate %d,%d\n", point.X, point.Y)
+			break
+		}
+	}
 }