Learning On the Way

22. Generate Parentheses

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

def generateParenthesis(self, n: int) -> List[str]: 
    ans = [] 
    def backtrack(s, left, right): 
        if left == right == n: 
            ans.append(s) 
            return 
            
        if left < n: 
            backtrack(s + '(', left + 1, right) 
            
        if left > right: 
            backtrack(s + ')', left, right + 1) 
            
    backtrack('', 0, 0) 
            
    return ans