<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 maxAreaOfIsland(vector<vector<int>>& grid) {
        int n = grid.size(), m = grid[0].size();
        int max_area = 0;
        vector<pair<int, int>> directions = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
        for (int k = 0; k < n; k++) {
            for (int l = 0; l < m; l++) {
                queue<pair<int, int>> q;
                if (grid[k][l] == 1) {
                    q.push(make_pair(k, l));
                    grid[k][l] = 0;
                }
                int cur_area = 0;
                while (!q.empty()) {
                    
                    pair<int, int> node = q.front();
                    q.pop();
                    cur_area++;
                    
                    for (auto [dy, dx] : directions) {
                        int new_y = node.first + dy;
                        int new_x = node.second + dx;
                        if (new_y >= 0 && new_y < n && new_x >= 0 && new_x < m) {
                            if (grid[new_y][new_x] == 1) {
                                q.push(make_pair(new_y, new_x));
                                grid[new_y][new_x] = 0;
                            }
                        }
                    }
                }
                max_area = max(max_area, cur_area);
            }    
        }
        
        return max_area;
    }
};*/
class Solution {
public:
    int dfs(vector<vector<int>>& grid, int y, int x, vector<vector<bool>>& visited, int rows, int columns) {
        int cur_area = 1;
        vector<pair<int, int>> directions = {{0, -1}, {-1, 0}, {0, 1}, {1, 0}};
        visited[y][x] = true;
        
        for (auto [dy, dx] : directions) {
            int new_y = y + dy;
            int new_x = x + dx;
            if (new_y >= 0 && new_y < rows && new_x >= 0 && new_x < columns && !visited[new_y][new_x] && grid[new_y][new_x] != 0) {
                cur_area += dfs(grid, new_y, new_x, visited, rows, columns);
            }
        }
        return cur_area;
    }
    int maxAreaOfIsland(vector<vector<int>>& grid) {
        int rows = grid.size();
        int columns = grid[0].size();
        vector<vector<bool>> visited(rows, vector<bool>(columns, false));
        int max_area = 0;
        
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < columns; j++) {
                if (!visited[i][j] && grid[i][j] != 0) {
                    max_area = max(max_area, dfs(grid, i, j, visited, rows, columns));
                }
            }
        }
        return max_area;
    }
};
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