<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:
    int x[4] = {-1, 0, 0, 1};
    int y[4] = {0, -1, 1, 0};

    bool isValid(int i, int j, int m, int n, vector<vector<int>>& grid) {
        if (i >= 0 and i < m and j >= 0 and j < n and grid[i][j] == 0)
            return true;
        return false;
    }

    void dfs(int i, int j, int m, int n, vector<vector<bool>>& visited, vector<vector<int>>& grid) {
        visited[i][j] = true;
        for (int k=0; k<4; k++) {
            if (isValid(i+x[k],j+y[k], m, n, grid)) {
                if (!visited[i+x[k]][j+y[k]]) {
                    dfs(i+x[k], j+y[k], m, n, visited, grid);
                }
            }
        }
    }

    int ff(vector<string>& grid) {
        if (!grid.size()) return 0;
        int m = grid.size()*3;
        int n = grid[0].size()*3;
        vector<vector<int>> newGrid(m, vector<int>(n, 0));
        vector<vector<bool>> visited(m, vector<bool>(n, false));
        for (int i=0; i<grid.size(); i++) {
            for (int j=0; j<grid[0].size(); j++) {
                if (grid[i][j] == '/') {
                    newGrid[i*3][j * 3 + 2] = 1;
                    newGrid[i * 3 + 1][j * 3 + 1] = 1;
                    newGrid[i * 3 + 2][j * 3] = 1;
                }
                else if (grid[i][j] == '\\') {
                    newGrid[i * 3][j * 3] = 1;
                    newGrid[i * 3 + 1][j * 3 + 1] = 1;
                    newGrid[i * 3 + 2][j * 3 + 2] = 1;
                }
            }
        }
        int count = 0;
        for (int i=0; i<m; i++) {
            for (int j=0; j<n; j++) {
                if (newGrid[i][j] == 0 and !visited[i][j]) {
                    dfs(i, j, m, n, visited, newGrid);
                    count++;
                }
            }
        }
        return count;
    } 

    int regionsBySlashes(vector<string>& grid) {
        return ff(grid);
    }
};
15903