【发布时间】：2013-03-29 18:08:38
【问题描述】：
我正在使用递归回溯算法创建一个迷宫生成器。但是，我的问题是每次运行程序时都会给出以下结果：
1 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 1 1
0 0 0 0 0 0 0 1 1 1
0 0 0 0 0 0 1 1 1 1
0 0 0 0 0 1 1 1 1 1
0 0 0 0 1 1 1 1 1 1
0 0 0 1 1 1 1 1 1 1
0 0 1 1 1 1 1 1 1 1
0 1 1 1 1 1 1 1 1 1
0 1 1 1 1 1 1 1 1 1
我的代码的一些背景知识： 构造函数用0填充迷宫int数组，在结束位置(0, 0)放一个1，然后调用backtrackGenerateMaze()方法随机生成一个迷宫。我认为问题可能是我没有墙，这可能会导致奇怪的事情发生。此外，对于方向：0 = 上，1 = 右，2 = 下，& 3 = 左。希望对您有所帮助。
这是我的代码（抱歉这么久，我一直在尝试使用 cmets 来调试它）：
public class Maze {
private int width, length;
private int[][] maze;
public Maze(int rows, int columns) {
width = columns;
length = rows;
maze = new int[rows][columns];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
maze[i][j] = 0;
}
}
maze[0][0] = 1;
backtrackGenerateMaze(rows - 1, columns - 1, 1);
}
/*
* THE PROBLEM MUST BE HERE IN THE backtrackGenerateMaze() METHOD
*/
private void backtrackGenerateMaze(int rows, int columns, int moveLength) {
if (rows == 0 && columns == 0) {
System.out.println("rows = " + rows);
System.out.println("length = " + length);
System.out.println("columns = " + columns);
System.out.println("width = " + width);
return;
}
int[] randDirs = generateRandomDirections();
for (int dir : randDirs) {
System.out.println("dir == " + dir);
System.out.println("rows == " + rows);
System.out.println("columns == " + columns + "\n");
if (dir == 0) {
System.out.println("rows - moveLength == " + (rows - moveLength));
System.out.println("valid(rows - moveLength, columns) == " + (valid(rows - moveLength, columns)));
System.out.println("isInRange(0, length, rows - moveLength, false) == " + (isInRange(0, length, rows - moveLength, false)));
if (valid(rows - moveLength, columns)
&& isInRange(0, length, rows - moveLength, false)
&& maze[rows - moveLength][columns] != 1) {
System.out.println("IF 0 is TRUE");
for (int i = 1; i <= moveLength; i++) {
maze[rows - moveLength][columns] = 1;
}
maze[rows][columns] = 1;
System.out.println("HERE 0");
backtrackGenerateMaze(rows - moveLength, columns, moveLength);
}
// System.out.println("RETURN DIR 0");
// return;
} else if (dir == 1) {
System.out.println("columns + moveLength = " + (columns + moveLength));
System.out.println("valid(rows, columns + moveLength) = " + (valid(rows, columns + moveLength)));
System.out.println();
if (valid(rows, columns + moveLength)) {
System.out.println("VALID 1 is TRUE");
if (isInRange(0, width, columns + moveLength, false)) {
System.out.println("isInRange() 1 is TRUE");
if (maze[rows][columns + moveLength] != 1) {
System.out.println("square != 1 is TRUE");
System.out.println("IF 1 is TRUE");
for (int i = 1; i <= moveLength; i++) {
maze[rows][columns + moveLength] = 1;
}
maze[rows][columns] = 1;
System.out.println("HERE 1");
backtrackGenerateMaze(rows, columns + moveLength, moveLength);
}
}
}
System.out.println("RETURN DIR 1");
return;
} else if (dir == 2) {
if (valid(rows + moveLength, columns)
&& isInRange(0, length, rows + moveLength, false)
&& maze[rows + moveLength][columns] != 1) {
System.out.println("IF 2 is TRUE");
for (int i = 1; i <= moveLength; i++) {
maze[rows + moveLength][columns] = 1;
}
maze[rows][columns] = 1;
System.out.println("HERE 2");
backtrackGenerateMaze(rows + moveLength, columns, moveLength);
}
System.out.println("RETURN DIR 2");
return;
} else if (dir == 3) {
if (valid(rows, columns - moveLength)
&& isInRange(0, width, columns - moveLength, false)
&& maze[rows][columns - moveLength] != 1) {
System.out.println("IF 3 is TRUE");
for (int i = 1; i <= moveLength; i++) {
maze[rows][columns - moveLength] = 1;
}
maze[rows][columns] = 1;
System.out.println("HERE 3");
backtrackGenerateMaze(rows + moveLength, columns - moveLength, moveLength);
}
System.out.println("RETURN DIR 3");
return;
}
}
System.out.println("--------------------");
}
public int[] generateRandomDirections() {
ArrayList<Integer> rands = new ArrayList<>();
for (int i = 0; i < 4; i++) {
rands.add(i);
}
Collections.shuffle(rands);
int[] ret = new int[4];
for (int i = 0; i < rands.size(); i++) {
ret[i] = rands.get(i);
}
return ret;
}
private boolean valid(int row, int column) {
return isInRange(0, maze.length - 1, row, true)
&& isInRange(0, maze[0].length - 1, column, true);
}
private boolean isInRange(int start, int end, int toCheck,
boolean inclusive) {
if (inclusive) {
return (toCheck >= start && toCheck <= end);
}
return (toCheck > start && toCheck < end);
}
@Override
public String toString() {
String ret = "";
for (int i = 0; i < maze.length; i++) {
for (int j = 0; j < maze[0].length; j++) {
ret += maze[i][j] + " ";
}
ret += "\n";
}
return ret;
}
}
...这是我用来运行它的 Main 方法：
public class MazeGame {
private static ArrayList<Maze> mazes = new ArrayList<>();
private static final int MAZE_SIZE = 10, NUM_MAZES = 1;
public static void main(String[] args) {
Maze temp;
for (int i = 0; i < NUM_MAZES; i++) {
temp = new Maze(MAZE_SIZE, MAZE_SIZE);
System.out.println(temp);
mazes.add(temp);
}
}
}
非常感谢任何帮助。
【问题讨论】：
-
如果我知道问题出在哪里我会的...但是代码太多很难追踪（尤其是随机部分）。
-
当然，但这对我们来说更难！您已经在 IDE 中进行了所有设置，准备就绪。恐怕你得先用调试器来解决这个问题。
-
那你建议我怎么做？如果你愿意，我可以把零件拿出来……
-
确实如此。删除与问题不直接相关的每一行代码。如果您知道某些代码路径未用于您的示例输入，那么也将它们删除（首先检查断言语句以进行仔细检查）。然后找到可能失败的最小/最简单的测试用例，看看是否可以逐步跟踪以找到导致不同行为的迭代。您现在还应该使用固定种子来生成随机数，以便在多次运行之间获得相同的行为。
标签： java recursion generator backtracking maze