<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 result = 1;
    // int n;
    // vector<vector<int>> end_pos;
    // void trace(int i, int j, vector<string>& grid){
    //     if(i == n- 1){
    //         result++;
    //         return;
    //     }
    //     bool traced = false;
    //     if(grid[i][j] == '/'){
    //         if(j == 0) result++;
    //         if(i + 1 < n && j - 1 >= 0 && grid[i + 1][j - 1] == '/'){
    //             if(grid[i][j - 1] != '\\'){
    //                 trace(i + 1, j - 1, grid);
    //                 traced = true;
    //             }
    //         }
    //         if(i + 1 < n && grid[i + 1][j] == '\\'){
    //             trace(i + 1, j, grid);
    //             traced = true;
    //         }
    //         if(!traced && j != 0){
    //             if(find(end_pos.begin(), end_pos.end(), {i, j + 1}) != end_pos.end()) result++;
    //             else end_pos.push_back({i, j + 1});
    //         }
    //     }
    //     else{
    //         if(j == n - 1) result++;
    //         if(i + 1 < n && grid[i + 1][j] == '/'){
    //             trace(i + 1, j, grid);
    //             traced = true;
    //         }
    //         if(i + 1 < n && j + 1 < grid.size() && grid[i + 1][j + 1] == '\\'){
    //             trace(i + 1, j + 1, grid);
    //             traced = true;
    //         }
    //         if(!traced && j != n - 1){
    //             if(find(end_pos.begin(), end_pos.end(), {i + 1, j + 1}) != end_pos.end()) result++;
    //             else end_pos.push_back({i + 1, j + 1});
    //         }
    //     }
    // }
    bool collected[90][90];
    void collect_island(int i, int j, vector<vector<int>>& g){
        int n = g.size();
        if(i<0||j<0||i>=n||j>=n) return;
        else if(g[i][j]==0||collected[i][j]==true)return;
        else{
            collected[i][j]=true;
            collect_island(i,j+1, g);
            collect_island(i,j-1, g);
            collect_island(i-1,j, g);
            collect_island(i+1,j, g);
        }
    }
    int regionsBySlashes(vector<string>& grid) {
        int n = grid.size();
        vector<vector<int>> g(n * 3);
        for(int i = 0; i < n * 3; i++){
            for(int j = 0; j < n * 3; j++){
                g[i].push_back(1);
            }
        }
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                if(grid[i][j] == '/'){
                    g[i * 3][j * 3 + 2] = 0;
                    g[i * 3 + 1][j * 3 + 1] = 0;
                    g[i * 3 + 2][j * 3] = 0;
                }
                else if(grid[i][j] =='\\'){
                    g[i * 3][j * 3] = 0;
                    g[i * 3 + 1][j * 3 + 1] = 0;
                    g[i * 3 + 2][j * 3 + 2] = 0;
                }
            }
        }
        for(int i=0;i<n * 3;i++){
            for(int j=0;j<n * 3;j++){
                collected[i][j]=false;
            }
        }
        int num=0;
        for(int i=0;i<n * 3;i++){
            for(int j=0;j<n * 3;j++){
                //cout<<g[0][0]<<endl;
                //cout<<collected[i][j]<<endl;
                if(g[i][j]==1&&collected[i][j]==false){
                    //cout<<"hi"<<endl;
                    num++;
                    collect_island(i, j, g);
                }
            }
        }
        return num;

        // n = grid.size();
        // end_pos.resize(n + 1);
        // for(auto pos:end_pos) pos.resize(n + 1)
        // for(int j = 0; j < n; j++){
        //     if(grid[0][j] != ' ') trace(0, j, grid);
        // }
        // return result;
    }
};
16666