<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 {
public:
    void dfs(vector<vector<int>> &matrix,vector<vector<bool>> &visit,int i,int j){
        if(i<0 || i>=matrix.size() || j<0 || j>=matrix[0].size() || visit[i][j] || matrix[i][j]==1){
            return;
        }

        visit[i][j]=true;
        dfs(matrix,visit,i+1,j);
        dfs(matrix,visit,i,j+1);
        dfs(matrix,visit,i-1,j);
        dfs(matrix,visit,i,j-1);
    }

    int regionsBySlashes(vector<string>& grid) {
        int n = grid.size();
        vector<vector<int>> matrix(3*n, vector<int>(3*n, 0));

        for(int i=0; i < grid.size(); i++) {
            for(int j=0; j < grid[i].size(); j++) {
                if(grid[i][j] == '/') {
                    matrix[3*i][3*j+2] = 1;
                    matrix[3*i+1][3*j+1] = 1;
                    matrix[3*i+2][3*j] = 1;
                }
                else if(grid[i][j] == '\\') {
                    matrix[3*i][3*j] = 1;
                    matrix[3*i+1][3*j+1] = 1;
                    matrix[3*i+2][3*j+2] = 1;
                }
            }
        }

        vector<vector<bool>> visit(3*n, vector<bool>(3*n, false));
        int cnt = 0;

        for(int i=0; i<3*n; i++) {
            for(int j=0; j<3*n; j++) {
                if(!visit[i][j] && matrix[i][j] == 0) {
                    dfs(matrix, visit, i, j);
                    cnt++;
                }
            }
        }

        return cnt;
    }
};

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