<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:
 int n,m;
   vector<vector<int>> d={{-1,0},{0,1},{1,0},{0,-1}};
     int bfs(int i,int j,vector<vector<int>> &v, vector<vector<int>> &vis){
        queue<pair<int,int>> q;
        q.push({i,j});
        vis[i][j]=1;
        int c=0;
        while(!q.empty()){
         int x=q.front().first;
         int y=q.front().second;c++;
         q.pop();
         for(int i=0;i<4;i++){
            int nx=x+d[i][0];
            int ny=y+d[i][1];
            if(nx<0 || nx>=n || ny<0 || ny>=m) continue;
            else {
                if(v[nx][ny]==1 && vis[nx][ny]==0){
                    vis[nx][ny]=1;
                    q.push({nx,ny});
                }
            }
         }
        }
        return c;
     }
    int maxAreaOfIsland(vector<vector<int>>& v) {
          n=v.size();m=v[0].size();int c=0;
       
         vector<vector<int>> vis(n,vector<int>(m,0));
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(vis[i][j]==0 && v[i][j]==1){
                    c=max(c,bfs(i,j,v,vis));
                }
            }
        }
        return c;

    }
};

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