Rotten Oranges

//{ Driver Code Starts
#include<bits/stdc++.h>
using namespace std;

// } Driver Code Ends
class Solution
{
    public:
    //Function to find minimum time required to rot all oranges.
    int orangesRotting(vector<vector<int>>& grid) {
        // Code here
        int n = grid.size();
        int m = grid[0].size();
        queue<pair<pair<int,int>,int>> q;
        int vis[n][m];
        int cntfresh=0;
        for(int i=0;i<grid.size();i++)
        {
            for(int j=0;j<grid[0].size();j++)
            {
                if(grid[i][j]==2)
                {
                    q.push({{i,j},0});
                    vis[i][j]=2;
                }
                else
                {
                    vis[i][j]=0;
                }
                if(grid[i][j]==1)
                {
                    cntfresh++;
                }
            }
        }
        int tm=0;
        int drow[] = {-1,0,1,0};
        int dcol[] = { 0,1,0,-1};
        int c=0;
        while(!q.empty())
        {
            int ni = q.front().first.first;
            int nj = q.front().first.second;
            int t = q.front().second;
            tm = max(tm,t);
            q.pop();

            for(int i=0;i<4;i++)
            {
                int row = ni+drow[i];
                int col = nj+dcol[i];
                if((row>=0 && row<n) && (col>=0 && col<m) && vis[row][col]==0 && grid[row][col]==1)
                {
                    q.push({{row,col},t+1});
                    vis[row][col]=2;
                    c++;
                }
            }
        }
        if(c!=cntfresh)
        {
            return -1;
        }
        return tm;
    }
};

//{ Driver Code Starts.
int main(){
    int tc;
    cin >> tc;
    while(tc--){
        int n, m;
        cin >> n >> m;
        vector<vector<int>>grid(n, vector<int>(m, -1));
        for(int i = 0; i < n; i++){
            for(int j = 0; j < m; j++){
                cin >> grid[i][j];
            }
        }
        Solution obj;
        int ans = obj.orangesRotting(grid);
        cout << ans << "\n";
    }
    return 0;
}
// } Driver Code Ends