🌅

solutions/day18/day18.go

@@ -0,0 +1,148 @@
+package day18
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+type Point struct {
+	x int
+	y int
+	z int
+}
+
+const (
+	Lava int = iota
+	Air
+	Steam
+)
+
+func surroundingPoints(point Point) []Point {
+	return []Point{
+		{point.x - 1, point.y, point.z},
+		{point.x + 1, point.y, point.z},
+		{point.x, point.y - 1, point.z},
+		{point.x, point.y + 1, point.z},
+		{point.x, point.y, point.z - 1},
+		{point.x, point.y, point.z + 1},
+	}
+}
+
+func countBlankSides(points map[Point]int, against int) int {
+	blankSides := 0
+	for point, original := range points {
+		if original == Lava {
+			pointBlankSides := 0
+			for _, surrounding := range surroundingPoints(point) {
+				if points[surrounding] == against {
+					pointBlankSides += 1
+				}
+			}
+			//fmt.Println("Point", point, "had", pointBlankSides, "blank sides.")
+			blankSides += pointBlankSides
+		}
+	}
+	return blankSides
+}
+
+func inUniverse(point Point, min Point, max Point) bool {
+	return point.x >= min.x && point.x <= max.x &&
+		point.y >= min.y && point.y <= max.y &&
+		point.z >= min.z && point.z <= max.x
+}
+
+func floodSteam(minPoint Point, maxPoint Point, points map[Point]int) {
+	stack := []Point{minPoint}
+
+	for len(stack) > 0 {
+		nextIdx := len(stack) - 1
+		next := stack[nextIdx]
+		stack = stack[0:nextIdx]
+
+		if inUniverse(next, minPoint, maxPoint) && points[next] == Air {
+			points[next] = Steam
+			stack = append(stack, surroundingPoints(next)...)
+		}
+	}
+}
+
+func findExtendedBoundingBox(points map[Point]int) (minPoint Point, maxPoint Point) {
+	minPoint = Point{1000000, 100000, 100000}
+	maxPoint = Point{0, 0, 0}
+
+	for point := range points {
+		if point.x < minPoint.x {
+			minPoint.x = point.x
+		}
+		if point.x > maxPoint.x {
+			maxPoint.x = point.x
+		}
+		if point.y < minPoint.y {
+			minPoint.y = point.y
+		}
+		if point.y > maxPoint.y {
+			maxPoint.y = point.y
+		}
+		if point.z < minPoint.z {
+			minPoint.z = point.z
+		}
+		if point.z > maxPoint.z {
+			maxPoint.z = point.z
+		}
+	}
+
+	fmt.Println("Min point", minPoint)
+	fmt.Println("Max point", maxPoint)
+
+	minPoint.x -= 1
+	minPoint.y -= 1
+	minPoint.z -= 1
+	maxPoint.x += 1
+	maxPoint.y += 1
+	maxPoint.z += 1
+
+	return
+}
+
+func Run(filename string) {
+	file, err := os.Open(filename)
+	if err != nil {
+		fmt.Println("Error opening file:", err)
+		return
+	}
+
+	scanner := bufio.NewScanner(file)
+	scanner.Split(bufio.ScanLines)
+	points := map[Point]int{}
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		var x int
+		var y int
+		var z int
+		fmt.Sscanf(line, "%d,%d,%d", &x, &y, &z)
+		point := Point{x, y, z}
+		points[point] = Lava
+	}
+	file.Close()
+
+	minPoint, maxPoint := findExtendedBoundingBox(points)
+
+	for x := minPoint.x; x <= maxPoint.x; x++ {
+		for y := minPoint.y; y <= maxPoint.y; y++ {
+			for z := minPoint.z; z <= maxPoint.z; z++ {
+				point := Point{x, y, z}
+				_, exists := points[point]
+				if !exists {
+					points[point] = Air
+				}
+			}
+		}
+	}
+
+	fmt.Println("Found", countBlankSides(points, Air), "blank sides in base solid.")
+	floodSteam(minPoint, maxPoint, points)
+	fmt.Println("Found", countBlankSides(points, Steam), "blank sides after filling interior.")
+
+}