<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:
    //3x3 blocks for each character ' ', '/' and '\\' respectively
    vector<vector<int>> empty = {{0,0,0},{0,0,0},{0,0,0}};
    vector<vector<int>> sb = {{0,0,1},{0,1,0},{1,0,0}};
    vector<vector<int>> cb = {{1,0,0},{0,1,0},{0,0,1}};
    //4 directions for dfs
    vector<int> x = {1,0,-1,0};
    vector<int> y = {0,1,0,-1};
    //To Store our binary matrix
    vector<vector<int>> mat;
    //Normal DFS to find number of islands
    void dfs(int i,int j){
        if(i < 0 || i >= mat.size() || j < 0 || j >= mat[0].size() || mat[i][j] == 1) return;
        mat[i][j] = 1;
        for(int k=0;k<4;k++){
            int newi = i+x[k];
            int newj = j+y[k];
            dfs(newi,newj);
        }
    }
    // To fill the our binary matrix with the blocks we made
    void filling(vector<vector<int>> &arr,int i){
        for(int k=0;k<3;k++){
            mat[i].push_back(arr[0][k]); 
            mat[i+1].push_back(arr[1][k]); 
            mat[i+2].push_back(arr[2][k]);
        }
    }
    int regionsBySlashes(vector<string>& grid) {
        mat.resize(grid.size()*3);
        int ind=0;
        //Fill with appropriate blocks 
        for(int i=0;i<grid.size();i++){
            for(int j=0;j<grid[i].size();j++){
                if(grid[i][j] == ' ') filling(empty,ind);
                else if(grid[i][j] == '/') filling(sb,ind);
                else filling(cb,ind);
            }
            ind+=3;
        }
        //Number of Islands
        int ans =0;
        for(int i=0;i<mat.size();i++){
            for(int j=0;j<mat[0].size();j++){
                if(mat[i][j] == 0){
                    dfs(i,j);
                    ans++;
                }
            }
        }
        return ans;
    }
};
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