Rotten_Oranges.cpp

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

// } Driver Code Ends
class Solution
{
public:
    int orangesRotting(vector<vector<int>> &grid)
    {

        int n = grid.size();
        int m = grid[0].size();

        int delRow[] = {-1, 0, +1, 0};
        int delCol[] = {0, +1, 0, -1};

        queue<pair<pair<int, int>, int>> q;
        int vis[n][m];

        for (int i = 0; i < n; i++)
        {
            for (int j = 0; j < m; j++)
            {
                if (grid[i][j] == 2)
                {
                    q.push({{i, j}, 0});
                    vis[i][j] = 2;
                }
                else
                    vis[i][j] = 0;
            }
        }

        int tm = 0;
        while (!q.empty())
        {
            int r = q.front().first.first;
            int c = q.front().first.second;
            int t = q.front().second;
            tm = max(tm, t);
            q.pop();

            for (int i = 0; i < 4; i++)
            {
                int nrow = r + delRow[i];
                int ncol = c + delCol[i];
                if (nrow >= 0 && nrow < n && ncol >= 0 && ncol < m &&
                    vis[nrow][ncol] != 2 && grid[nrow][ncol] == 1)
                {
                    q.push({{nrow, ncol}, t + 1});
                    vis[nrow][ncol] = 2;
                }
            }
        }

        for (int i = 0; i < n; i++)
        {
            for (int j = 0; j < m; j++)
            {
                if (vis[i][j] != 2 && grid[i][j] == 1)
                    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