<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 dfs(self, grid: List[List[int]], i, j, k):
        if not(0 <= i < len(grid) and 0 <= j < len(grid) and grid[i][j] == 0):
            return
        grid[i][j] = k
        for d in [(-1 , 0), (1, 0), (0, -1), (0, 1)]:
            self.dfs(grid, i + d[0], j + d[1], k)

    def regionsBySlashes(self, grid: List[str]) -> int:
        ng = []
        for row in grid:
            ng.append([])
            ng.append([])
            ng.append([])
            for elem in row:
                match elem:
                    case " ":
                        ng[-1].extend([0, 0, 0])
                        ng[-2].extend([0, 0, 0])
                        ng[-3].extend([0, 0, 0])
                    case "\\":
                        ng[-1].extend([0, 0, 1])
                        ng[-2].extend([0, 1, 0])
                        ng[-3].extend([1, 0, 0])
                    case "/":
                        ng[-1].extend([1, 0, 0])
                        ng[-2].extend([0, 1, 0])
                        ng[-3].extend([0, 0, 1])

        answer = 0
        for i in range(len(ng)):
            for j in range(len(ng)):
                if ng[i][j] == 0:
                    answer += 1
                    self.dfs(ng, i, j, answer)

        return answer
16689