HTTP Server just to serve the madness

maze/maze.go

@@ -26,6 +26,18 @@ var (
 // The algorithm is randomized depth-first carving with one entrance on the top border
 // and one exit on the bottom border.
 func Generate(width, height int) (Grid, error) {
+	return generate(width, height, rand.IntN)
+}
+
+// GenerateWithSeed creates a maze grid with deterministic randomness.
+//
+// The same width, height, and seed always produce the same maze.
+func GenerateWithSeed(width, height int, seed uint64) (Grid, error) {
+	rng := rand.New(rand.NewPCG(seed, seed^0x9e3779b97f4a7c15))
+	return generate(width, height, rng.IntN)
+}
+
+func generate(width, height int, intN func(int) int) (Grid, error) {
 	if width <= 0 || height <= 0 {
 		return nil, ErrInvalidDimensions
 	}
@@ -51,7 +63,7 @@ func Generate(width, height int) (Grid, error) {
 	for len(stackX) > 0 {
 		last := len(stackX) - 1
 		x, y := stackX[last], stackY[last]
-		dirs := shuffledDirections()
+		dirs := shuffledDirections(intN)
 
 		carved := false
 		for _, d := range dirs {
@@ -85,7 +97,7 @@ func Generate(width, height int) (Grid, error) {
 		}
 	}
 	if len(topChoices) > 0 {
-		entranceX := topChoices[rand.IntN(len(topChoices))]
+		entranceX := topChoices[intN(len(topChoices))]
 		grid[0][entranceX] = 1
 	}
 
@@ -96,7 +108,7 @@ func Generate(width, height int) (Grid, error) {
 		}
 	}
 	if len(bottomChoices) > 0 {
-		exitX := bottomChoices[rand.IntN(len(bottomChoices))]
+		exitX := bottomChoices[intN(len(bottomChoices))]
 		grid[height-1][exitX] = 1
 	}
 
@@ -227,10 +239,10 @@ func directionDelta(direction uint8) (dx, dy int) {
 	}
 }
 
-func shuffledDirections() [4]uint8 {
+func shuffledDirections(intN func(int) int) [4]uint8 {
 	dirs := [4]uint8{0, 1, 2, 3}
 	for i := 3; i > 0; i-- {
-		j := rand.IntN(i + 1)
+		j := intN(i + 1)
 		dirs[i], dirs[j] = dirs[j], dirs[i]
 	}
 	return dirs