<p>An <code>n x n</code> grid is composed of <code>1 x 1</code> squares where each <code>1 x 1</code> square consists of a <code>&#39;/&#39;</code>, <code>&#39;\&#39;</code>, or blank space <code>&#39; &#39;</code>. These characters divide the square into contiguous regions.</p>

<p>Given the grid <code>grid</code> represented as a string array, return <em>the number of regions</em>.</p>

<p>Note that backslash characters are escaped, so a <code>&#39;\&#39;</code> is represented as <code>&#39;\\&#39;</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/1.png" style="width: 200px; height: 200px;" />
<pre>
<strong>Input:</strong> grid = [&quot; /&quot;,&quot;/ &quot;]
<strong>Output:</strong> 2
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/2.png" style="width: 200px; height: 198px;" />
<pre>
<strong>Input:</strong> grid = [&quot; /&quot;,&quot;  &quot;]
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 3:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2018/12/15/4.png" style="width: 200px; height: 200px;" />
<pre>
<strong>Input:</strong> grid = [&quot;/\\&quot;,&quot;\\/&quot;]
<strong>Output:</strong> 5
<strong>Explanation: </strong>Recall that because \ characters are escaped, &quot;\\/&quot; refers to \/, and &quot;/\\&quot; refers to /\.
</pre>

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

<ul>
	<li><code>n == grid.length == grid[i].length</code></li>
	<li><code>1 &lt;= n &lt;= 30</code></li>
	<li><code>grid[i][j]</code> is either <code>&#39;/&#39;</code>, <code>&#39;\&#39;</code>, or <code>&#39; &#39;</code>.</li>
</ul>

class Solution:
    def expandGrid(self, grid: list[str])->int:
        n = len(grid)
        matrix = []
        for i in range(n * 3):
            row = [0] * (n * 3)
            matrix.append(row)

        for r in range(n):
            for c in range(len(grid[r])):
                if grid[r][c] == "/":
                    matrix[r * 3 + 2][c * 3] = 1
                    matrix[r * 3 + 1][c * 3 + 1] = 1
                    matrix[r * 3][c * 3 + 2] = 1
                elif grid[r][c] == "\\":
                    matrix[r * 3][c * 3] = 1
                    matrix[r * 3 + 1][c * 3 + 1] = 1
                    matrix[r * 3 + 2][c * 3 + 2] = 1
        
        return matrix

    def regionsBySlashes(self, grid: List[str]) -> int:
        matrix = self.expandGrid(grid)
        n = len(matrix)
        visited = set()
        numRegions = 0

        def visitRegion(r: int, c: int):
            if (
                r < 0 or r >= n or
                c < 0 or c >= n or
                (r, c) in visited or
                matrix[r][c] == 1
            ):
                return
            
            visited.add((r, c))
            directions = [[1, 0], [-1, 0], [0, 1], [0, -1]]
            for deltaR, deltaC in directions:
                visitRegion(r + deltaR, c + deltaC)

        
        for r in range(n):
            for c in range(n):
                if (r, c) not in visited and matrix[r][c] == 0:
                    visitRegion(r, c)
                    numRegions += 1
        
        return numRegions

23866