<p>You are given an <code>m x n</code> matrix <code>board</code> containing <strong>letters</strong> <code>&#39;X&#39;</code> and <code>&#39;O&#39;</code>, <strong>capture regions</strong> that are <strong>surrounded</strong>:</p>

<ul>
	<li><strong>Connect</strong>: A cell is connected to adjacent cells horizontally or vertically.</li>
	<li><strong>Region</strong>: To form a region <strong>connect every</strong> <code>&#39;O&#39;</code> cell.</li>
	<li><strong>Surround</strong>: The region is surrounded with <code>&#39;X&#39;</code> cells if you can <strong>connect the region </strong>with <code>&#39;X&#39;</code> cells and none of the region cells are on the edge of the <code>board</code>.</li>
</ul>

<p>A <strong>surrounded region is captured</strong> by replacing all <code>&#39;O&#39;</code>s with <code>&#39;X&#39;</code>s in the input matrix <code>board</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">board = [[&quot;X&quot;,&quot;X&quot;,&quot;X&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;O&quot;,&quot;O&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;X&quot;,&quot;O&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;O&quot;,&quot;X&quot;,&quot;X&quot;]]</span></p>

<p><strong>Output:</strong> <span class="example-io">[[&quot;X&quot;,&quot;X&quot;,&quot;X&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;X&quot;,&quot;X&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;X&quot;,&quot;X&quot;,&quot;X&quot;],[&quot;X&quot;,&quot;O&quot;,&quot;X&quot;,&quot;X&quot;]]</span></p>

<p><strong>Explanation:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/xogrid.jpg" style="width: 367px; height: 158px;" />
<p>In the above diagram, the bottom region is not captured because it is on the edge of the board and cannot be surrounded.</p>
</div>

<p><strong class="example">Example 2:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">board = [[&quot;X&quot;]]</span></p>

<p><strong>Output:</strong> <span class="example-io">[[&quot;X&quot;]]</span></p>
</div>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == board.length</code></li>
	<li><code>n == board[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 200</code></li>
	<li><code>board[i][j]</code> is <code>&#39;X&#39;</code> or <code>&#39;O&#39;</code>.</li>
</ul>

class Solution {
private:
    bool
    getRegion(vector<vector<char>>& board, bool**& visited, int i, int j, vector<tuple<int,int>>& region)
    {
       if(i >= board.size())
        return false;

        if(j >= board[i].size())
            return false;

        if(visited[i][j])
            return true;

        visited[i][j] = true;

        if(board[i][j] == 'X')
        {
            return true;
        }

        region.push_back({i,j});
        bool res = true;

        // UP 
        res &= getRegion(board, visited, i - 1, j, region);

        // RIGHT
        res &= getRegion(board, visited, i, j + 1, region);

        // DOWN
        res &= getRegion(board, visited, i + 1, j, region);

        // LEFT
        res &= getRegion(board, visited, i, j - 1, region);

        return res;
    }
public:
    void solve(vector<vector<char>>& board) {
        bool** visited = new bool*[board.size()];
        for(int i = 0; i < board.size(); i++)
        {
            visited[i] = new bool[board[i].size()] { false };
        }

        for(int i = 0; i < board.size(); i++)
        {
            for(int j = 0; j < board[i].size(); j++)
            {
                if(visited[i][j] || board[i][j] == 'X')
                    continue;

                vector<tuple<int,int>> region;
                if(getRegion(board, visited, i, j, region))
                {
                    for(tuple<int,int>& regionPoint:region)
                    {
                        board[get<0>(regionPoint)][get<1>(regionPoint)] = 'X';
                    }
                }
            }
        }
        
        for(int i = 0; i < board.size(); i++)
        {
            delete[] visited[i];
        }

        delete[] visited;
    }
};
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