<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:
    int regionsBySlashes(vector<string>& grid) 
    {
        int n = grid.size();
        vector<vector<int>> nGrid(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] == '/')
                {
                    nGrid[3*i][3*j+2] = 1;
                    nGrid[3*i+1][3*j+1] = 1;
                    nGrid[3*i+2][3*j] = 1;
                }
                else if(grid[i][j] == '\\')
                {
                    nGrid[3*i][3*j] = 1;
                    nGrid[3*i+1][3*j+1] = 1;
                    nGrid[3*i+2][3*j+2] = 1;
                }
            }
        }

        int count = 0;
        for(int i=0; i<3*n; i++)
        {
            for(int j=0; j<3*n; j++)
            {
                if(nGrid[i][j] == 0)
                {
                    count++;
                    nGrid[i][j] = 1;
                    bfs(nGrid, i, j);
                }
            }
        }
        return count;
    }
    
    void bfs(vector<vector<int>>& nGrid, int i, int j)
    {
        vector<vector<int>> dir{
            {1, 0},
            {-1, 0},
            {0, 1},
            {0, -1}
        };
        
        queue<pair<int, int>> q;
        q.push(make_pair(i, j));
        while(!q.empty())
        {
            pair<int, int> cur = q.front();
            q.pop();
            for(int i=0; i<4; i++)
            {
                int nx = cur.first + dir[i][0], ny = cur.second + dir[i][1];
                cout << nx << " " << ny << endl;
                if(isValid(nx, ny, nGrid.size()) && nGrid[nx][ny] == 0)
                {
                    nGrid[nx][ny] = 1;
                    q.push(make_pair(nx, ny));
                }
            }
        }
    }
    
    bool isValid(int i, int j, int n)
    {
        if(i<0)
            return false;
        if(j<0)
            return false;
        if(i>=n)
            return false;
        if(j>=n)
            return false;
        return true;
    }
};
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