<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>> &g, int n, int i, int j)
    {
        int dirs[4][2] = {{-1, 0}, {0, -1}, {1, 0}, {0, 1}};
        g[i][j] = 1;

        for(auto d: dirs)
        {
            int x = i + d[0];
            int y = j + d[1];

            if(x < 0 || y < 0 || x >= n || y >= n || g[x][y] == 1)
                continue;

            dfs(g, n, x, y);
        }
    }

    int regionsBySlashes(vector<string>& grid) {
        int n = grid.size();
        int n3 = n * 3;

        vector<vector<int>> g(n3, vector<int>(n3, 0));

        for(int i=0; i<n; i++){
            for(int j=0; j<n; j++){
                if(grid[i][j] == '/'){
                    int x = i*3, y = j*3+2;
                    int c = 3;

                    while(c--)
                        g[x++][y--] = 1;
                }
                else if(grid[i][j] == '\\'){
                    int x = i*3, y = j*3;
                    int c = 3;

                    while(c--)
                        g[x++][y++] = 1;
                }
            }
        }

        int cc = 0;

        for(int i=0; i<n3; i++)
            for(int j=0; j<n3; j++)
                if(g[i][j] == 0)
                {
                    cc++;
                    dfs(g, n3, i, j);
                }

        return cc;
    }
};
14683