<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 check(string &s, int n, int o, int c, vector<string> &ans){
        if(o==n && c==n){
            ans.push_back(s);
        }

        //considering open
        if(o<=n){
            string one=s;
            one.push_back('(');
            check(one,n,o+1,c,ans);
        }

        //considering closed
        if(o>c && c<n){
            string two=s;
            two.push_back(')');
            check(two,n,o,c+1,ans);
        }
     
    }
    vector<string> generateParenthesis(int n) {
        vector<string> ans;
        string s="";
        check(s,n,0,0,ans);
        return ans;
    }
};


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