<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> result;

    void solve(string& str, int n, int open, int close) {

        if (str.length() == 2 * n) {

            result.push_back(str);

            return;

        }

        if (open < n) {

            str.push_back('(');

            solve(str, n, open + 1, close);

            str.pop_back();

        }

        if (close < open) {

            str.push_back(')');

            solve(str, n, open, close + 1);

            str.pop_back();

        }

    }

    vector<string> generateParenthesis(int n) {

        string str = "";

        int open = 0, close = 0;

        solve(str, n, open, close);

        return result;

    }

};

    
        
    




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