<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:
    void solve(int& n, string& temp, int open, int close, vector<string>& ans) {
        if(temp.size() == 2*n) {
            ans.push_back(temp);
            return;
        }

        if(open < n) {
            temp.push_back('(');
            solve(n, temp, open + 1, close, ans);
            temp.pop_back();
        }

        if(close < open) {
            temp.push_back(')');
            solve(n, temp, open, close + 1, ans);
            temp.pop_back();
        }
    }
    vector<string> generateParenthesis(int n) {
        vector<string> ans;
        string temp = "";
        int open = 0, close = 0;
        solve(n, temp, open, close, ans);
        return ans;
    }
};
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