<p>Given <code>n</code> pairs of parentheses, write a function to <em>generate all combinations of well-formed parentheses</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> n = 3
<strong>Output:</strong> ["((()))","(()())","(())()","()(())","()()()"]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> n = 1
<strong>Output:</strong> ["()"]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 8</code></li>
</ul>

class Solution {
public:


    vector<string> generateParenthesis(int n) {
        vector<string> ans;
        if(n == 0){
            ans.push_back("");
            return ans;
        }
        if(n == 1){
            ans.push_back("()");
            return ans;
        }
        else{
            vector<string> temp = generateParenthesis(n-1);
            for(int i = 0; i < n; i++){
                vector<string> f = generateParenthesis(i);
                vector<string> b = generateParenthesis(n-i-1);
                for(int j = 0; j < f.size(); j++){
                    for(int k = 0; k < b.size(); k++){
                        ans.push_back('('+f[j]+')'+b[k]);
                    }
                }
            }
        }
        return ans;
    }
};
19083