<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 isSafe(int i,int j , vector<vector<int>>& grid , vector<vector<bool>> &vis)
    {
        int row = grid.size();
        int col = grid[0].size();
        if(i<0 || i>=row || j<0 || j>=col)
        {
            return false;
        }
        if(grid[i][j]==0 || vis[i][j])
        {
            return false;
        }
        return true;
    }

    int bfs(int i,int j , vector<vector<int>>& grid , vector<vector<bool>> &vis)
    {
        int row = grid.size();
        int col = grid[0].size();
        queue<pair<int,int>> q;
        q.push({i,j});
        vis[i][j] = true;
        int area=0;
        while(!q.empty())
        {
            pair<int,int> node = q.front();
            q.pop();
            
            area++;
            int x = node.first;
            int y = node.second;
            vector<int> dx = {1,0,-1,0};
            vector<int> dy = {0,1,0,-1};
            for(int k=0;k<4;k++)
            {
                int newX = x+dx[k];
                int newY = y+dy[k];
                if(isSafe(newX,newY,grid,vis))
                {
                    
                    q.push({newX,newY});
                    vis[newX][newY] = true;
                }
            }
        }
        
        return area;
    }

    int maxAreaOfIsland(vector<vector<int>>& grid) {
        int ans = 0;
        int row = grid.size();
        int col = grid[0].size();
        vector<vector<bool>> vis(row , vector<bool> (col , false));
        for(int i=0;i<row;i++)
        {
            for(int j=0;j<col;j++)
            {
                if(!vis[i][j] && grid[i][j])
                {
                    ans = max(ans , bfs(i,j,grid,vis));
                }
            }
        }
        return ans;
    }
};
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