feat: solve p2

internal/2015/DaySix/code.go

@@ -71,5 +71,55 @@ func PartOne(data []string) int {
 }
 
 func PartTwo(data []string) int {
-	return 0
+	grid := make([]int, 1000*1000)
+
+	for _, line := range data {
+		var op string
+		var x1, y1, x2, y2 int
+
+		switch {
+		case strings.HasPrefix(line, "turn on "):
+			op = "on"
+			line = strings.TrimPrefix(line, "turn on ")
+		case strings.HasPrefix(line, "turn off "):
+			op = "off"
+			line = strings.TrimPrefix(line, "turn off ")
+		case strings.HasPrefix(line, "toggle "):
+			op = "toggle"
+			line = strings.TrimPrefix(line, "toggle ")
+		default:
+			continue
+		}
+
+		parts := strings.Split(line, " through ")
+		firstCoordinates := strings.Split(parts[0], ",")
+		secondCoordinates := strings.Split(parts[1], ",")
+
+		x1, _ = strconv.Atoi(firstCoordinates[0])
+		y1, _ = strconv.Atoi(firstCoordinates[1])
+		x2, _ = strconv.Atoi(secondCoordinates[0])
+		y2, _ = strconv.Atoi(secondCoordinates[1])
+
+		for y := y1; y <= y2; y++ {
+			for x := x1; x <= x2; x++ {
+				idx := y*1000 + x
+				switch op {
+				case "on":
+					grid[idx]++
+				case "off":
+					if grid[idx] > 0 {
+						grid[idx]--
+					}
+				case "toggle":
+					grid[idx] += 2
+				}
+			}
+		}
+	}
+
+	total := 0
+	for _, brightness := range grid {
+		total += brightness
+	}
+	return total
 }