As_Far_From_Land_As_Possible.txt

class Solution {
public:
    int maxDistance(vector<vector<int>>& grid)
    {
       queue<pair<int,int>> que;
       for(int i=0;i<grid.size();i++)
       {
           for(int j=0;j<grid[i].size();j++)
           {
               if(grid[i][j])
               {
               que.push(make_pair(i,j));
               grid[i][j]=0;
               }
               else
                   grid[i][j]=INT_MAX;
            
           }
           
       }
         int n=grid.size();
        if(que.empty() || que.size()== n*n) return -1;
        int maxim=-1;
        vector<vector<int>> vec = {{-1,0},{1,0},{0,1},{0,-1}};
        int dis=0;
        while(!que.empty())
        {
            pair<int,int> p=que.front();
            que.pop();
            int a=p.first;
            int b=p.second;
            for(auto it : vec)
            {
                int ao=a+it[0];
                int bo=b+it[1];
                if(ao>=0 && ao<grid.size() && bo>=0 && bo<grid[0].size())
                {  
                    if(grid[ao][bo]==INT_MAX)
                {
                    que.push({ao,bo});
                    grid[ao][bo]=grid[a][b]+1;
                }
                }
            }
        }
        int ans = 0;
       
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            //cout<<grid[i][j]<<' ';
         ans = max(ans,grid[i][j]);   
        }
        //cout<<endl;           
    }
    return ans;
    }
};