<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 par[2000];
    int size[2000];
    void make(int i)
    {
        size[i]=1;
        par[i]=i;
    }

    int find(int i)
    {
        if(par[i]==i) return par[i];
        return par[i]=find(par[i]);
    }

    void Union(int a,int b)
    {
        a=find(a);
        b=find(b);
        if(a!=b)
        {
          if(size[a]<size[b])
          {
           swap(a,b);
        }
        par[b]=a;
        size[a]+=size[b];
        }
    }

    int regionsBySlashes(vector<string>& grid) {
        int n=grid.size();
        int cnt=1;

        for(int i=0;i<(n+1)*(n+1);i++)
        {
             make(i);
        }

        for(int i=0;i<n;i++)
        {
            Union(i,i+1);
        }

        for(int i=(n+1)*(n);i<(n+1)*(n+1)-1;i++)
        {
            Union(i,i+1);
        }

        for(int i=0;i<n*(n+1);i+=n+1)
        {
            Union(i,i+(n+1));
        }
        
        for(int i=n;i<(n+1)*(n+1)-1;i+=n+1)
        {
            Union(i,i+(n+1));
        }


        for(int i=0;i<n;i++)
        {
          for(int j=0;j<n;j++)
          {
             if(grid[i][j]=='/')
             {
                int u=(i+1)*(n+1)+j;
                int v=i*(n+1)+j+1;
                if(find(u)!=find(v))
                Union(u,v);
                else
                {
                    cnt++;
                }
             }
             else if(grid[i][j]=='\\')
             {
                int u=(i)*(n+1)+j;
                int v=(i+1)*(n+1)+j+1;
                if(find(u)!=find(v))
                Union(u,v);
                else
                {
                    cnt++;
                }
             }
          }
        }
        return cnt;

    }
};
11328