<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:
    def generateParenthesis(self, n: int) -> List[str]:

        stack = []
        res = []


        def backtrack(open, closed):

            if open==closed==n:
                res.append("".join(stack))
                return
            
            if open < n:
                stack.append("(")
                backtrack(open+1, closed)
                stack.pop()
            
            if closed < open:
                stack.append(")")
                backtrack(open, closed + 1)
                stack.pop()
            
        backtrack(0,0)
        return res
        
16800