Generate Parentheses

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

A combination is well-formed if every opening bracket has a matching closing bracket, in the correct order.

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Example 1

Input: n = 3
Output: ["((()))", "(()())", "(())()", "()(())", "()()()"]
Explanation: All 5 valid combinations of 3 pairs of parentheses are listed.

Example 2

Input: n = 1
Output: ["()"]
Explanation: With 1 pair, the only valid combination is "()".

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Constraints

• 1 <= n <= 8