迷官

說明
由於迷宮的設計，老鼠走迷宮的入口至出口路徑可能不只一條，如何求出所有的路徑呢？

解法
求所有路徑看起來複雜但其實更簡單，只要在老鼠走至出口時顯示經過的路徑，然後退回上一格重新選擇下一個位置繼續遞迴就可以了，比求出單一路徑還簡單，我們的程式只要作一點修改就可以了。
演算法

Procedure GO(maze[]) [
VISIT(maze, STARTI, STARTJ);
]

Procedure VISIT(maze[], i, j) [
maze[i][j] = 1;

IF(i == ENDI AND j == ENDJ) [
// FIND A ROUTE, PRINT THE ROUTE
]

IF(maze[i][j+1] == 0)
VISIT(maze, i, j+1);
IF(maze[i+1][j] == 0)
VISIT(maze, i+1, j);
IF(maze[i][j-1] == 0)
VISIT(maze, i, j-1);
if(maze[i-1][j] == 0)
VISIT(maze, i-1, j);

maze[i][j] = 0;
]

• Java program

public class Mouse {
   private int startI, startJ;  // 入口
   private int endI, endJ;  // 出口
  
   public static void main(String[] args) {
       int maze[][] = {{2, 2, 2, 2, 2, 2, 2, 2, 2},
                       {2, 0, 0, 0, 0, 0, 0, 0, 2},
                       {2, 0, 2, 2, 0, 2, 2, 0, 2},
                       {2, 0, 2, 0, 0, 2, 0, 0, 2},
                       {2, 0, 2, 0, 2, 0, 2, 0, 2},
                       {2, 0, 0, 0, 0, 0, 2, 0, 2},
                       {2, 2, 0, 2, 2, 0, 2, 2, 2},
                       {2, 0, 0, 0, 0, 0, 0, 0, 2},
                       {2, 2, 2, 2, 2, 2, 2, 2, 2}};
      
       System.out.println("顯示迷宮：");
       for(int i = 0; i < maze.length; i++) {
           for(int j = 0; j < maze[0].length; j++)
               if(maze[i][j] == 2)
                   System.out.print("█");
               else
                   System.out.print("  ");
           System.out.println();
       }

       Mouse mouse = new Mouse();
       mouse.setStart(1, 1);
       mouse.setEnd(7, 7);
      
       mouse.go(maze);
   }
  
   public void setStart(int i, int j) {
       this.startI = i;
       this.startJ = j;
   }
  
   public void setEnd(int i, int j) {
       this.endI = i;
       this.endJ = j;
   }
  
   public void go(int[][] maze) {
       visit(maze, startI, startJ);
   }
  
   private void visit(int[][] maze, int i, int j) {
       maze[i][j] = 1;

       if(i == endI && j == endJ) {
           System.out.println("\n找到出口！");
           for(int m = 0; m < maze.length; m++) {
               for(int n = 0; n < maze[0].length; n++) {
                   if(maze[m][n] == 2)
                       System.out.print("█");
                   else if(maze[m][n] == 1)
                       System.out.print("◇");
                   else
                       System.out.print("  ");
               }
               System.out.println();
           }
       }

       if(maze[i][j+1] == 0)
           visit(maze, i, j+1);
       if(maze[i+1][j] == 0)
           visit(maze, i+1, j);
       if(maze[i][j-1] == 0)
           visit(maze, i, j-1);
       if(maze[i-1][j] == 0)
           visit(maze, i-1, j);
     
       maze[i][j] = 0;
   }
}