<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 {
private:
    vector<pair<int, int>> dirs = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
    unordered_map<char, vector<vector<int>>> mp = {
        {'/', {{0, 0, 1}, {0, 1, 0}, {1, 0, 0}}},
        {'\\', {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}},
        {' ', {{0, 0, 0}, {0, 0, 0}, {0, 0, 0}}}
    };

    vector<vector<int>> zoom(vector<string>& grid){
        int n = grid.size();
        vector<vector<int>> res(3*n, vector<int>(3*n, 0));
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                for(int r = 0; r < 3; r++){
                    for(int c = 0; c < 3; c++){
                        res[3*i+r][3*j+c] = mp[grid[i][j]][r][c]; 
                    }
                }
            }
        }
        return res;
    }

    void markRegion(vector<vector<int>>& grid, int r, int c){
        if(grid[r][c] == -1 || grid[r][c] == 1) return;
        grid[r][c] = -1;
        int n = grid.size();
        for(auto& [x, y]: dirs){
            int new_x = r + x, new_y = c + y;
            if(new_x >= 0 && new_y >= 0 && new_x < n && new_y < n) markRegion(grid, new_x, new_y);
        }
    }
    
public:
    int regionsBySlashes(vector<string>& grid) {
        int cnt = 0;
        vector<vector<int>> zoomed = zoom(grid);
        int n = zoomed.size();
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                if(zoomed[i][j] == -1 || zoomed[i][j] == 1) continue;
                cnt++;
                markRegion(zoomed, i, j);
            }
        }
        return cnt;
    }
};
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