<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]:
        result = []
        def mainBackTrack(current,opened,closed):
            if opened == n and closed == n:
                result.append(current)
                return
            if closed != n and opened != n:
                mainBackTrack(current + "(" , opened + 1 , closed)
            if opened >closed:
                mainBackTrack(current + ")" , opened  , closed + 1)
        mainBackTrack("", 0 ,0 )
        return result
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