<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 bfs(vector<vector<int>> &grid,int i,int j, int m,vector<vector<bool>> &visited) {
        int iadd[4]={0,-1,0,1};
        int jadd[4]={-1,0,1,0};

        queue<pair<int,int>> q;
        q.push({i,j});
        visited[i][j]=true;
        while(!q.empty()) {
            pair<int,int> p=q.front();q.pop();
            for(int k=0;k<4;k++) {
                int x=p.first+iadd[k];
                int y=p.second+jadd[k];
                if(x<0||x>=m||y<0||y>=m) continue;
                if(grid[x][y]==1) continue;
                if(visited[x][y]) continue;
                q.push({x,y});
                visited[x][y]=true;
            }
        }
    }

    void dfs(vector<vector<int>> &grid,int i, int j, int m, vector<vector<bool>> &visited) {
        int iadd[4]={0,-1,0,1};
        int jadd[4]={-1,0,1,0};
        
        visited[i][j]=true;
        for(int k=0;k<4;k++) {
            int x=i+iadd[k];
            int y=j+jadd[k];
            if(x<0||x>=m||y<0||y>=m) continue;
            if(grid[x][y]==1) continue;
            if(visited[x][y]) continue;
            dfs(grid,x,y,m,visited);
        }
    }

    int regionsBySlashes(vector<string>& grid) {
        int n=grid.size();
        int m=3*n;
    
        vector<vector<int>> grid1(m,vector<int>(m,0));
        for(int i=0;i<n;i++) {
            for(int j=0;j<n;j++) {
                if(grid[i][j]=='/') {
                    int i1=3*i;
                    int j1=3*j;
                    grid1[i1][j1+2]=1;
                    grid1[i1+1][j1+1]=1;
                    grid1[i1+2][j1]=1;
                }
                else if(grid[i][j]=='\\') {
                    int i1=3*i;
                    int j1=3*j;
                    grid1[i1][j1]=1;
                    grid1[i1+1][j1+1]=1;
                    grid1[i1+2][j1+2]=1;
                }
            }
        }

        int cnt=0;
        vector<vector<bool>> visited(m,vector<bool>(m,false));
        for(int i=0;i<m;i++) {
            for(int j=0;j<m;j++) {
                if(grid1[i][j]==1) continue;
                if(visited[i][j]) continue;
                cnt++;
                //bfs(grid1,i,j,m,visited);
                dfs(grid1,i,j,m,visited);
            }
        }
        return cnt;
    }
};
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