Solving Maze using Backtracking C++

Question

I have got this maze of 2d matrix. '@' indicates the start and '#' indicates the end. 0 means the path is blocked and 1 means that you can pass through. The program needs to solve the maze and print the co-ordinates of each element in the path it found.

Example Input:
5 10
@ 1 1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0 0 1
0 1 0 1 0 1 1 1 0 1
1 1 1 1 0 1 0 0 0 1
# 0 0 1 1 1 1 1 1 1

First line is the row and column of the matrix.

#include<bits/stdc++.h>
using namespace std;


void findPath(int i, int j, vector<vector<string>> &maze, vector<vector<string>> &visited, int endX, int endY, int maxRow, int maxCol){

    if(i == endX && j == endY){
        return;
    }

    cout << i << " " << j << endl;

    visited[i][j] = "1";
    if(maze[i][j + 1] == "1" && visited[i][j + 1] != "1" && j + 1 < maxCol){
        findPath(i, j + 1, maze, visited, endX, endY, maxRow, maxCol);
    }
    if(maze[i + 1][j] == "1" && visited[i + 1][j] != "1" && i + 1 < maxRow){
        findPath(i + 1, j, maze, visited, endX, endY, maxRow, maxCol);
    }
    if(maze[i][j - 1] == "1" && visited[i][j - 1] != "1" && j - 1 >= 0){
        findPath(i, j - 1, maze, visited, endX, endY, maxRow, maxCol);
    }
    if(maze[i - 1][j] == "1" && visited[i - 1][j] != "1" && i - 1 >= 0){
        findPath(i - 1, j, maze, visited, endX, endY, maxRow, maxCol);
    }
    visited[i][j] = "0";
}

int main()
{
    freopen("input.txt", "r", stdin);

    int row, col;
    cin >> row >> col;
    
    vector<vector<string>> maze(row, vector<string>(col));
    vector<vector<string>> visited(row, vector<string>(col));


    for(int i = 0; i < row; i++){
        for(int j = 0; j < col; j++){
            cin >> maze[i][j];
        }
    }

    int startX, startY, endX, endY;
    for(int i = 0; i < row; i++){
        for(int j = 0; j < col; j++){
            if(maze[i][j] == "@"){
                startX = i;
                startY = j;
                maze[i][j] = "1";
            }
            if(maze[i][j] == "#"){
                endX = i;
                endY = j;
                maze[i][j] = "1";
            }
        }
    }

    findPath(startX, startY, maze, visited, endX, endY, row, col);
}

I made this code but it ends in segmentation fault and no output. It prints the co-ordinates for the initial row but then when it has to go down, it breaks.

My Output:
0 0
0 1
0 2
0 3
0 4
0 5
0 6
0 7
0 8
0 9

Is my approach wrong or have I missed something please help.

n. m. could be an AI · Accepted Answer · 2024-03-29 18:37:26Z

0

if(maze[i][j + 1] == "1" && visited[i][j + 1] != "1" && j + 1 < maxCol)

j + 1 < maxCol is a correct check but it's too late. maze[i][j + 1] and visited[i][j + 1] have already been accessed. You need to do bounds checking before you access the arrays, not after. Same thing with all other if statements.

if(j + 1 < maxCol && maze[i][j + 1] == "1" && visited[i][j + 1] != "1")

answered Mar 29, 2024 at 18:37

n. m. could be an AI

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