<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:
    def solve(self, board: List[List[str]]) -> None:
        """
        Do not return anything, modify board in-place instead.
        """
        height = len(board)
        width = len(board[0])
        visited = [[0 for _ in range(width)] for _ in range(height)]

        for i in range(height):
            print(board[i])
        print()
        
        for i in range(height):
            for j in range(width):
                if visited[i][j] == 0:
                    visited[i][j] = 1
                    if board[i][j] == "O":
                        pending = []
                        curRegion = []
                        curRegion.append([i, j])
                        if i == 0 or i == height-1 or j == 0 or j == width-1:
                            pending.append([-1, -1])

                        while len(curRegion) > 0:
                            curCell = curRegion.pop(0)
                            pending.append(curCell)
                            curH = curCell[0]
                            curW = curCell[1]

                            if curH-1 >= 0 and board[curH-1][curW] == "O" and visited[curH-1][curW] == 0:
                                visited[curH-1][curW] = 1
                                if curH - 1 == 0:
                                    pending.insert(0, [-1, -1])
                                curRegion.append([curH-1, curW])

                            if curH+1 <= height-1 and board[curH+1][curW] == "O" and visited[curH+1][curW] == 0:
                                visited[curH+1][curW] = 1
                                if curH + 1 == height - 1:
                                    pending.insert(0, [-1, -1])
                                curRegion.append([curH+1, curW])

                            if curW-1 >= 0 and board[curH][curW-1] == "O" and visited[curH][curW-1] == 0:
                                visited[curH][curW-1] = 1
                                if curW - 1 == 0:
                                    pending.insert(0, [-1, -1])
                                curRegion.append([curH, curW-1])

                            if curW+1 <= width-1 and board[curH][curW+1] == "O" and visited[curH][curW+1] == 0:
                                visited[curH][curW+1] = 1
                                if curW + 1 == width - 1:
                                    pending.insert(0, [-1, -1])
                                curRegion.append([curH, curW+1])

                        if len(pending) > 0 and pending[0] != [-1, -1]:
                            print(pending)
                            for idx in pending:
                                board[idx[0]][idx[1]] = "X"

                if i == 0 and j == 0:
                    for i in range(height):
                        print(visited[i])
                    print()
                    
        return

21350