rottenoranges.cpp

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

int orangesRotting(vector<vector<int>> grid) {
        if(grid.empty()) return 0;
        int m = grid.size(), n = grid[0].size(), days = 0, tot = 0, cnt = 0;
        queue<pair<int, int>> rotten;
        for(int i = 0; i < m; ++i){
            for(int j = 0; j < n; ++j){
                if(grid[i][j] != 0) tot++;
                if(grid[i][j] == 2) rotten.push({i, j});
            }
        }
        
        int dx[4] = {0, 0, 1, -1};
        int dy[4] = {1, -1, 0, 0};
        
        while(!rotten.empty()){
            int k = rotten.size();
            cnt += k; 
            while(k--){
                int x = rotten.front().first, y = rotten.front().second;
                rotten.pop();
                for(int i = 0; i < 4; ++i){
                    int nx = x + dx[i], ny = y + dy[i];
                    if(nx < 0 || ny < 0 || nx >= m || ny >= n || grid[nx][ny] != 1) 
					continue;
                    grid[nx][ny] = 2;
                    rotten.push({nx, ny});
                }
            }
            if(!rotten.empty()) days++;
        }
        
        return tot == cnt ? days : -1;
}


int main()
{
    int m,n;
    cout<<"Enter the number of rows and columns: ";
    cin>>m>>n;
    vector<vector<int>> grid;
    for(int i = 0; i < m; i++)
    {  
        grid.push_back(vector<int>());
        for(int j = 0; j < n; j++)
        {
            int z;
            cin>>z;
            grid[i].push_back(z);
        }   
    }
    cout<<orangesRotting(grid);
    return 0;
}