Rotting_Oranges.cpp

class Solution {
public:
    int orangesRotting(vector<vector<int>>& grid) {

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

        int vis[n][m];
        queue < pair< pair< int,int >,int > > q;
        int fresh=0;
        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;
                }
                if(grid[i][j]==1)
                    fresh++;
            }
        }

        int tm=0;

        int cnt=0;
        while(!q.empty())
        {
             int delrow[]={1,0,-1,0};
        int delcol[]={0,-1,0,1};
        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 && grid[nrow][ncol]==1 && vis[nrow][ncol]!=2)
            {
                q.push({{nrow,ncol},t+1});
                vis[nrow][ncol]=2;
                cnt++;

            }
        }
        }

              if(cnt != fresh) return -1;

        return tm;
    }
};