<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 bfs(vector<vector<int>>& grid,int i,int j,vector<vector<int>>& vis)
    {
        int ans = 1;
        queue<pair<int,int>> q;
        q.push({i,j});
        int n = grid.size();
        int m = grid[0].size();

        int delrow[] = {-1,0,1,0};
        int delcol[] = {0,1,0,-1};

        while(!q.empty())
        {
            int row = q.front().first;
            int col = q.front().second;
            q.pop();

            vis[row][col] = 1;

            for(int i = 0;i<4;i++)
            {
                int nrow = row + delrow[i];
                int ncol = col + delcol[i];

                if(nrow >= 0 && nrow < n && ncol >=0 && ncol < m && grid[nrow][ncol] == 1 && !vis[nrow][ncol])
                {
                    ans++;
                    vis[nrow][ncol] = 1;
                    q.push({nrow,ncol});
                }
            }
        }
        return ans;

    }
    int maxAreaOfIsland(vector<vector<int>>& grid) {
        int n = grid.size();
        int m = grid[0].size();
        vector<vector<int>> vis(n,vector<int>(m,0));

        int ans = 0;

        for(int i = 0; i< n;i++)
        {
            for(int j = 0 ; j<m;j++)
            {
                if(grid[i][j]==1 && !vis[i][j]){
                    ans = max(ans,bfs(grid,i,j,vis));
                }
            }
        }
        return ans;
    }
};
31850