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Can a mouse in a maze make multiple steps or jumps?

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Release: 2023-08-29 12:17:06
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Can a mouse in a maze make multiple steps or jumps?

The mouse in the maze problem is one of the well-known backtracking problems. Here we will see that the problem remains almost unchanged. Suppose an NxN maze M is given. The starting point is the upper left corner M[0, 0], and the end point is the lower right corner M[N – 1, N – 1]. A mouse is placed at the starting point. Our goal is to find a path from the starting point to the end point that allows the mouse to reach its destination. Here mice can jump (variant). Now there are some restrictions

  • The mouse can move right or down.
  • A 0 in a cell in the maze means that the cell is blocked.
  • Non-zero cells represent valid paths.
  • The number in a cell indicates the maximum number of jumps the rat can make from that cell.
  • ul>

    Algorithm

    ratInMaze

    begin
       if destination is reached, then
          print the solution matrix
       else
          1. Place the current cell inside the solution matrix as 1
          2. Move forward or jump (check max jump value) and recursively check if move leads to solution or not.
          3. If the move taken from the step 2 is not correct, then move down, and check it leads to the solution or not
          4. If none of the solutions in step 2 and 3 are correct, then make the current cell 0.
       end if
    end
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    Example

    #include <iostream>
    #define N 4
    using namespace std;
    void dispSolution(int sol[N][N]) {
       for (int i = 0; i < N; i++) {
          for (int j = 0; j < N; j++)
             cout << sol[i][j] << " ";
          cout << endl;
       }
    }
    bool isSafe(int maze[N][N], int x, int y) { //check whether x,y is valid or not
       // when (x, y) is outside of the maze, then return false
       if (x >= 0 && x < N && y >= 0 && y < N && maze[x][y] != 0)
          return true;
       return false;
    }
    bool ratMazeSolve(int maze[N][N], int x, int y, int sol[N][N]) {
       if (x == N - 1 && y == N - 1) { //if destination is found, return true
          sol[x][y] = 1;
          return true;
       }
       if (isSafe(maze, x, y)) {
          sol[x][y] = 1; //mark 1 into solution matrix
          for (int i = 1; i <= maze[x][y] && i < N; i++) {
             if (ratMazeSolve(maze, x + i, y, sol)) //move right
                return true;
             if (ratMazeSolve(maze, x, y + i, sol)) //move down
                return true;
          }
          sol[x][y] = 0; //if the solution is not valid, then make it 0
          return false;
       }
       return false;
    }
    bool solveMaze(int maze[N][N]) {
       int sol[N][N] = { { 0, 0, 0, 0 },
          { 0, 0, 0, 0 },
          { 0, 0, 0, 0 },
          { 0, 0, 0, 0 }
       };
       if (!ratMazeSolve(maze, 0, 0, sol)) {
          cout << "Solution doesn&#39;t exist";
          return false;
       }
       dispSolution(sol);
       return true;
    }
    main() {
       int maze[N][N] = { { 2, 1, 0, 0 },
          { 3, 0, 0, 1 },
          { 0, 1, 0, 1 },
          { 0, 0, 0, 1 }
       };
       solveMaze(maze);
    }
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    Output

    1 0 0 0
    1 0 0 1
    0 0 0 1
    0 0 0 1
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source:tutorialspoint.com
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