<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:
    vector<int>v;
    vector<pair<int, int>> chk = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
    int row, col, cnt=0;

    int maxAreaOfIsland(vector<vector<int>>& grid) {
        row = grid.size();
        col = grid[0].size();
        for(int i=0; i<row; i++) {
            for(int j=0; j<col; j++) {
                if(grid[i][j] == 1) {
                    DFS(i, j, grid);
                    v.push_back(cnt);
                    cnt=0;
                }
            }
        }
        int mx = 0;
        for(auto it: v) {
            if(mx < it) { mx = it; }
        }
        return mx;
    }

    void DFS(int i, int j, vector<vector<int>>& grid) {
                cnt++;
        grid[i][j] = 0;

        for(auto it: chk) {
            int ci = i + it.first;
            int cj = j + it.second;

            if(valid(ci, cj) && grid[ci][cj] != 0) {
                DFS(ci, cj, grid);
            }
        }
    }

    bool valid(int i, int j) {
        return (i >= 0 && j >= 0 && i < row && j < col);
    }
};
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