<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>> &grid, int i, int j){
        int m = grid.size();
        int n = grid[0].size();
        grid[i][j] = 1;
        if(i-1>=0 && grid[i-1][j] == 0) dfs(grid,i-1,j);
        if(i+1<m && grid[i+1][j] == 0) dfs(grid,i+1,j);
        if(j-1>=0 && grid[i][j-1] == 0) dfs(grid,i,j-1);
        if(j+1<n && grid[i][j+1] == 0) dfs(grid,i,j+1);
    }

    // int dr[4]={0,0,1,-1},dc[4]={1,-1,0,0};
    // void dfs(int r,int c,int n,vector<vector<int>> &mat){
    //     mat[r][c]=1;
    //     for(int k=0;k<4;k++){
    //         int nr = r + dr[k],nc = c + dc[k];
    //         if(nr>=0 && nr<n && nc>=0 && nc<n && mat[nr][nc]==0)
    //             dfs(nr,nc,n,mat);
    //     }
    // }

    int regionsBySlashes(vector<string>& grid) {
        int size = grid.size();
        int pointsperside = size + 1;
        int totalpoints = pointsperside * pointsperside;
        vector<int> parray(totalpoints,-1);
        for(int i=0; i<pointsperside; i++){
            for(int j=0; j<pointsperside; j++){
                if(i == 0 || j == 0 || i == (pointsperside - 1) || j == (pointsperside - 1)){
                    int point = i * pointsperside + j;
                    parray[point] = 0;
                }
            }
        }
        int sections = 1;
        parray[0] = -1;
        for(int i=0; i< size;i++){
            for(int j=0;j< size; j++){
                if(grid[i][j] == '/'){
                    int tr = i*pointsperside + (j+1);
                    int bl = (i+1)*pointsperside + j;
                    sections += unionset(parray,tr,bl);
                }
                else if(grid[i][j] == '\\'){
                    int tr = i*pointsperside + j;
                    int bl = (i+1)*pointsperside + (j+1);
                    sections += unionset(parray,tr,bl);

                }
            }
        }
        return sections;
    }
    int findparent(vector<int> &parray, int x){
        if(parray[x] == -1)
            return x;

        
        return parray[x] = findparent(parray,parray[x]);
    }
    int unionset(vector<int> &parray, int tr, int bl){
        int ptr = findparent(parray,tr);
        int pbl = findparent(parray,bl);

        if(ptr == pbl){
            return 1;
        }

        parray[ptr] = pbl;
        return 0;
    }
};
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