Day 24: Part 1

Signed-off-by: James Griffin <james@unsupervised.ca>

twentyfour/day_twentyfour.go

@@ -0,0 +1,95 @@
+package twentyfour
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+type lobby struct {
+	instructions []string
+	tiles        map[string]bool
+}
+
+func (l *lobby) load(filename string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	l.tiles = map[string]bool{}
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		l.instructions = append(l.instructions, scanner.Text())
+	}
+
+	return nil
+}
+
+func (l *lobby) layout() {
+	for _, instruction := range l.instructions {
+		north := false
+		south := false
+		x, y, z := 0, 0, 0
+		for i := 0; i < len(instruction); i++ {
+			switch string(instruction[i]) {
+			case "e":
+				if north {
+					x++
+					z--
+					north = false
+				} else if south {
+					z++
+					y--
+					south = false
+				} else {
+					x++
+					y--
+				}
+			case "w":
+				if north {
+					y++
+					z--
+					north = false
+				} else if south {
+					z++
+					x--
+					south = false
+				} else {
+					x--
+					y++
+				}
+			case "n":
+				north = true
+			case "s":
+				south = true
+			}
+		}
+		tileID := fmt.Sprintf("%d,%d,%d", x, y, z)
+		l.tiles[tileID] = !l.tiles[tileID]
+	}
+}
+
+func (l *lobby) countTiles() (black, white int) {
+	for _, t := range l.tiles {
+		if t {
+			black++
+		} else {
+			white++
+		}
+	}
+
+	return black, white
+}
+
+// PartOne How many tiles are left black
+func PartOne() string {
+	l := lobby{}
+	l.load("twentyfour/input.txt")
+
+	l.layout()
+	black, _ := l.countTiles()
+
+	return fmt.Sprintf("There are %d black tiles", black)
+}