Find the number of islands.cpp

    private:
    void bfs(int i,int j, vector<vector<int>>&vis,vector<vector<char>>&grid){
        vis[i][j] = 1;
        queue<pair<int,int>>q;
        q.push({i,j});
        int n = grid.size();
        int m = grid[0].size();
        while(!q.empty()){
            int row = q.front().first;
            int col = q.front().second;
            q.pop();
            for(int delrow = -1; delrow<=1; delrow++){
                for(int delcol=-1; delcol<=1; delcol++){
                    int nrow = row + delrow;
                    int ncol = col + delcol;
                    if(nrow >=0 && nrow < n && ncol >=0 && ncol < m && !vis[nrow][ncol]
                    && grid[nrow][ncol] == '1'){
                        vis[nrow][ncol] = 1;
                        q.push({nrow,ncol});
                    }
                }
            }
        }
    }
  public:
    // Function to find the number of islands.
    int numIslands(vector<vector<char>>& grid) {
        int n = grid.size();
        int m = grid[0].size();
        vector<vector<int>>vis(n,vector<int>(m,0));
        int cnt =0;
        for(int i=0; i<n; i++){
            for(int j=0; j<m; j++){
                if(!vis[i][j] && grid[i][j] == '1'){
                    cnt++;
                    bfs(i,j,vis,grid);
                }
            }
        }
        return cnt;
        // Code here
    }