A-M baby

Task/Maze-generation/Java/maze-generation.java

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+package org.rosettacode;
+
+import java.util.Random;
+import java.util.Collections;
+import java.util.Arrays;
+
+/*
+ * recursive backtracking algorithm
+ * shamelessly borrowed from the ruby at
+ * http://weblog.jamisbuck.org/2010/12/27/maze-generation-recursive-backtracking
+ */
+public class MazeGenerator {
+	private final int x;
+	private final int y;
+	private final int[][] maze;
+	private static final Random rand = new Random();
+
+	public MazeGenerator(int x, int y) {
+		this.x = x;
+		this.y = y;
+		maze = new int[this.x][this.y];
+		generateMaze(0, 0);
+	}
+
+	public void display() {
+		for (int i = 0; i < y; i++) {
+			// draw the north edge
+			for (int j = 0; j < x; j++) {
+				System.out.print((maze[j][i] & 1) == 0 ? "+---" : "+   ");
+			}
+			System.out.println("+");
+			// draw the west edge
+			for (int j = 0; j < x; j++) {
+				System.out.print((maze[j][i] & 8) == 0 ? "|   " : "    ");
+			}
+			System.out.println("|");
+		}
+		// draw the bottom line
+		for (int j = 0; j < x; j++) {
+			System.out.print("+---");
+		}
+		System.out.println("+");
+	}
+
+	private void generateMaze(int cx, int cy) {
+		DIR[] dirs = DIR.values();
+		Collections.shuffle(Arrays.asList(dirs));
+		for (DIR dir : dirs) {
+			int nx = cx + dir.dx;
+			int ny = cy + dir.dy;
+			if (between(nx, x) && between(ny, y)
+					&& (maze[nx][ny] == 0)) {
+				maze[cx][cy] |= dir.bit;
+				maze[nx][ny] |= dir.opposite.bit;
+				generateMaze(nx, ny);
+			}
+		}
+	}
+
+	private static boolean between(int v, int upper) {
+		return (v >= 0) && (v < upper);
+	}
+
+	private enum DIR {
+		N(1, 0, -1), S(2, 0, 1), E(4, 1, 0), W(8, -1, 0);
+		private final int bit;
+		private final int dx;
+		private final int dy;
+		private DIR opposite;
+
+		// use the static initializer to resolve forward references
+		static {
+			N.opposite = S;
+			S.opposite = N;
+			E.opposite = W;
+			W.opposite = E;
+		}
+
+		private DIR(int bit, int dx, int dy) {
+			this.bit = bit;
+			this.dx = dx;
+			this.dy = dy;
+		}
+	};
+
+	public static void main(String[] args) {
+		int x = args.length >= 1 ? (Integer.parseInt(args[0])) : 8;
+		int y = args.length == 2 ? (Integer.parseInt(args[1])) : 8;
+		MazeGenerator maze = new MazeGenerator(x, y);
+		maze.display();
+	}
+
+}