<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(int row, int col, vector<vector<bool>> &visited, vector<vector<int>> &GRID)
    {
        int N = GRID.size();
        visited[row][col] = true;
        int delRow[4] = {0,1,0,-1};
        int delCol[4] = {-1,0,1,0};
        queue<pair<int,int>>q;
        q.push({row,col});
        while(!q.empty())
        {
            int Row = q.front().first;
            int Col = q.front().second;
            q.pop();
            for(int i=0; i<4; i++)
            {
                int Crow = Row + delRow[i];
                int Ccol = Col + delCol[i];
                if( Crow>=0 && Crow<N && Ccol>=0 && Ccol<N && GRID[Crow][Ccol] == 0 
                && !visited[Crow][Ccol] ){
                    visited[Crow][Ccol] = true;
                    q.push({Crow, Ccol});
                }
            }
        }
    }

    int regionsBySlashes(vector<string>& grid) {
        int n = grid.size();
        vector<vector<int>> GRID(3*n,vector<int>(3*n,0));
        for(int i=0; i<n; i++)
        {
            for(int j=0; j<n; j++)
            {
                if(grid[i][j] == '/'){
                    GRID[3*i+2][3*j] = 1;
                    GRID[3*i][3*j+2] = 1;
                    GRID[3*i+1][3*j+1] = 1;
                }
                else if(grid[i][j] == '\\'){
                    GRID[3*i][3*j] = 1;
                    GRID[3*i+1][3*j+1] = 1;
                    GRID[3*i+2][3*j+2] = 1;
                }
                // cout << grid[i][j] << " ";
            }
            // cout << endl;
        }
        // for(int i=0; i<3*n; i++)
        // {
        //     for(int j=0; j<3*n; j++)
        //     {
        //         cout << GRID[i][j] << " ";
        //     }
        //     cout << endl;
        // }
        int count = 0;
        vector<vector<bool>>visited(3*n, vector<bool>(3*n,false));
        for(int i=0; i<3*n; i++)
        {
            for(int j=0; j<3*n; j++)
            {
                if(!visited[i][j] && GRID[i][j] == 0){
                    count++;
                    dfs(i,j,visited,GRID);
                }
            }
        }
        return count;
    }
};
20326