<p>You are given an <code>m x n</code> binary matrix <code>grid</code>. An island is a group of <code>1</code>&#39;s (representing land) connected <strong>4-directionally</strong> (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.</p>

<p>The <strong>area</strong> of an island is the number of cells with a value <code>1</code> in the island.</p>

<p>Return <em>the maximum <strong>area</strong> of an island in </em><code>grid</code>. If there is no island, return <code>0</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/01/maxarea1-grid.jpg" style="width: 500px; height: 310px;" />
<pre>
<strong>Input:</strong> grid = [[0,0,1,0,0,0,0,1,0,0,0,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,1,1,0,1,0,0,0,0,0,0,0,0],[0,1,0,0,1,1,0,0,1,0,1,0,0],[0,1,0,0,1,1,0,0,1,1,1,0,0],[0,0,0,0,0,0,0,0,0,0,1,0,0],[0,0,0,0,0,0,0,1,1,1,0,0,0],[0,0,0,0,0,0,0,1,1,0,0,0,0]]
<strong>Output:</strong> 6
<strong>Explanation:</strong> The answer is not 11, because the island must be connected 4-directionally.
</pre>

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

<pre>
<strong>Input:</strong> grid = [[0,0,0,0,0,0,0,0]]
<strong>Output:</strong> 0
</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;= 50</code></li>
	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
</ul>

class Solution {
public:

    bool isPossible(int x,int y,int m,int n){
        if(x<0 || x>=m || y<0 || y>=n){
            return false;
        }

        return true;
    }
    //dfs
    void dfs(vector<vector<int>>& grid,int m,int n,int x,int y,int& ans,bool** visited){
        visited[x][y]=true;
        ans+=1;
        vector<int> r={-1,+1,0,0};
        vector<int> c={0,0,-1,1};
        for(int i=0;i<4;i++){
            int rx=x+r[i];
            int ry=y+c[i];
            if(isPossible(rx,ry,m,n) && visited[rx][ry]==false && grid[rx][ry]==1){
                dfs(grid,m,n,rx,ry,ans,visited);
            }
        }
        return;        
    }

    int maxAreaOfIsland(vector<vector<int>>& grid) {
        int m=grid.size();
        int n=grid[0].size();
        bool** visited =new bool*[m];
        for(int i=0;i<m;i++){
            visited[i]=new bool[n]();
        }

        int ans=0;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                if(grid[i][j]==1){
                    int temp=0;
                    dfs(grid,m,n,i,j,temp,visited);
                    ans=max(ans,temp);
                }
            }
        }

        return ans;
        
    }
};
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