<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 {
    int geti(int i, int j, bool second, vector<string>& grid){
        return 2*i+ (int )second + j*grid.size()*2;
    }
    void dfs(vector<vector<int>> &g, vector<int> &vis, int index){
        vis[index]=1;
        cout<<"at index "<<index<<endl;
        for(int i=0;i<g[index].size();i++){
            if(vis[g[index][i]]==0){
                dfs(g,vis,g[index][i]);
            }
        }
    }
public:
    int regionsBySlashes(vector<string>& grid) {
        vector<vector<int>> g(grid.size()*grid.size()*2, vector<int>());
        vector<int> vis(grid.size()*grid.size()*2, 0);
        for(int i=0;i<grid.size();i++){
            for(int j=0;j<grid[i].length();j++){
                int first = geti(j,i,0,grid);
                int second = geti(j,i,1,grid);
                // cout<<first<<" "<<second<<" ";
                if(grid[i][j]==' '){
                    g[first].push_back(second);
                    g[second].push_back(first);
                    // cout<<" conn "<<first<<" "<<second<<endl;
                }
                if(j!=0){
                    int second_p = geti(j-1,i,1,grid);
                    g[first].push_back(second_p);
                    g[second_p].push_back(first);
                    // cout<<" conn "<<first<<" "<<second_p<<"z"<<endl;
                }

                if(i!=0){
                    int first_p=geti(j,i-1,0,grid),second_p=geti(j,i-1,1,grid);
                    if(grid[i][j]=='/'){
                        if(grid[i-1][j]=='/'){
                            g[first].push_back(second_p);
                            g[second_p].push_back(first);
                            // cout<<" conn "<<first<<" "<<second_p<<"q"<<i<<" "<<j<<"---"<<endl;
                        }
                        else if(grid[i-1][j]=='\\'){
                            g[first].push_back(first_p);
                            g[first_p].push_back(first);
                            // cout<<" conn "<<first<<" "<<first_p<<"w"<<endl;
                        }
                        else{
                            g[first].push_back(first_p);
                            g[first_p].push_back(first);
                            // cout<<" conn "<<first<<" "<<first_p<<"e"<<endl;
                        }
                    }else if(grid[i][j]=='\\'){
                        if(grid[i-1][j]=='/'){
                            g[second].push_back(second_p);
                            g[second_p].push_back(second);
                            // cout<<" conn "<<second<<" "<<second_p<<"a"<<endl;
                        }
                        else if(grid[i-1][j]=='\\'){
                            g[second].push_back(first_p);
                            g[first_p].push_back(second);
                            // cout<<" conn "<<second<<" "<<first_p<<"b"<<endl;
                        }
                        else{
                            g[second].push_back(first_p);
                            g[first_p].push_back(second);
                            // cout<<" conn "<<second<<" "<<first_p<<"c"<<endl;
                        }
                    }
                    else{
                        if(grid[i-1][j]=='/'){
                            g[first].push_back(second_p);
                            g[second_p].push_back(first);
                            // cout<<" conn "<<first<<" "<<second_p<<endl;
                        }
                        else if(grid[i-1][j]=='\\'){
                            g[first].push_back(first_p);
                            g[first_p].push_back(first);
                            // cout<<" conn "<<first<<" "<<first_p<<endl;
                        }
                        else{
                            g[first].push_back(first_p);
                            g[first_p].push_back(first);
                            // cout<<" conn "<<first<<" "<<first_p<<endl;
                        }
                    }
                }
            }
            // cout<<endl;
        }
        int ans=0;
        for(int i=0;i<grid.size()*grid.size()*2; i++){
            if(vis[i]==0){
                // cout<<"i "<<i<<" \n\n";
                ans++;
                dfs(g,vis,i);
            }
        }
        return ans;
        
    }
};

/*


i,j,0/1

2*i + (0/1)


//
\\

/\
\/


\\
\\




*/
19106