<p>In a gold mine <code>grid</code> of size <code>m x n</code>, each cell in this mine has an integer representing the amount of gold in that cell, <code>0</code> if it is empty.</p>

<p>Return the maximum amount of gold you can collect under the conditions:</p>

<ul>
	<li>Every time you are located in a cell you will collect all the gold in that cell.</li>
	<li>From your position, you can walk one step to the left, right, up, or down.</li>
	<li>You can&#39;t visit the same cell more than once.</li>
	<li>Never visit a cell with <code>0</code> gold.</li>
	<li>You can start and stop collecting gold from <strong>any </strong>position in the grid that has some gold.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> grid = [[0,6,0],[5,8,7],[0,9,0]]
<strong>Output:</strong> 24
<strong>Explanation:</strong>
[[0,6,0],
 [5,8,7],
 [0,9,0]]
Path to get the maximum gold, 9 -&gt; 8 -&gt; 7.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1,0,7],[2,0,6],[3,4,5],[0,3,0],[9,0,20]]
<strong>Output:</strong> 28
<strong>Explanation:</strong>
[[1,0,7],
 [2,0,6],
 [3,4,5],
 [0,3,0],
 [9,0,20]]
Path to get the maximum gold, 1 -&gt; 2 -&gt; 3 -&gt; 4 -&gt; 5 -&gt; 6 -&gt; 7.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 15</code></li>
	<li><code>0 &lt;= grid[i][j] &lt;= 100</code></li>
	<li>There are at most <strong>25 </strong>cells containing gold.</li>
</ul>

class Solution {
public:
int n;
int m;
bool isValid(int x,int y){
    if(x<0 || y<0 || x>=n || y>=m)
    return false;
    return true;
}
int find(int u,int v, vector<vector<int>>& grid , vector<vector<bool>>&vis,int &count ,int &ans){
    if(grid[u][v]==0 || vis[u][v]==true)
    return 0;

    count=count+grid[u][v];
    vis[u][v]=true;

    int row[4]={-1,1,0,0};
    int col[4]={0,0,-1,1};

     for(int i=0;i<4;i++){
        int x=u+row[i];
        int y=v+col[i];

        if(isValid(x,y)){
          find(x,y,grid,vis,count,ans);
          ans=max(ans,count);
        }
     }
     vis[u][v]=false;
     count=count-grid[u][v];

     return ans;
}
    int getMaximumGold(vector<vector<int>>& grid) {
        
        n=grid.size();
        m=grid[0].size();
        int res=0;
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                int count=0;
                vector<vector<bool>>vis(n,vector<bool>(m,false));
                if(grid[i][j]!=0){
                    int ans=INT_MIN;
                   ans = find(i,j,grid,vis,count,ans);
                  //cout<<i<<" "<<j<<" "<<ans;
                   res=max(res,ans);
                }
            }
        }
        return res;
    }
};
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