<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 regionsBySlashes(self, grid: List[str]) -> int:
        cell_len = 5
        self.pixel_grid = [[0 for _ in range(cell_len*len(grid))] for _ in range(cell_len*len(grid))]
        for i, row in enumerate(grid):
            for j, elem in enumerate(row):
                if elem=='/':
                    for k in range(cell_len):
                        self.pixel_grid[cell_len*i+k][cell_len*j+cell_len-1-k]=1
                elif elem=='\\':
                    for k in range(cell_len):
                        self.pixel_grid[cell_len*i+k][cell_len*j+k]=1
        region_num = 0
        for i in range(len(self.pixel_grid)):
            for j in range(len(self.pixel_grid)):
                if self.pixel_grid[i][j]!=1:
                    self.dfs((i,j))
                    region_num+=1
        return region_num



    def dfs(self, curr_cell):
        cx, cy = curr_cell
        dirs = [[-1,0],[0,-1], [0,1] , [1,0]]
        for dir_ in dirs:
            dx, dy = dir_
            nx, ny = cx+dx, cy+dy
            if 0<=nx<len(self.pixel_grid) and 0<=ny<len(self.pixel_grid[0]):
                if self.pixel_grid[nx][ny]!=1:
                    self.pixel_grid[nx][ny]=1
                    self.dfs((nx,ny))
21148