GenerateParenthesis.py

# Question Link - https://leetcode.com/problems/generate-parentheses/description/?envType=study-plan-v2&envId=top-interview-150

class Solution:

    def generateParenthesis(self, n: int) -> List[str]:
        stack = [] #Store the single parenthesis 
        res = []   #res of the combination of valid parenthesis

        def generate(openN , closeN):
            if openN == closeN == n:
                res.append("".join(stack))
                return

            if openN < n :
                stack.append('(')
                generate(openN + 1 , closeN)
                stack.pop()

            if closeN < openN :
                stack.append(')')
                generate(openN , closeN + 1)
                stack.pop()

        generate(0 , 0)
        return res
        


        # Solution 1
        # ans = []
        # self.generate(0 , 0 , n ,"" ,ans)
        # return ans

    # def generate(self, open_count , close_count , n , current , ans):
    #     if open_count == close_count == n:
    #         ans.append(current)
    #         return

    #     if open_count < n:
    #         self.generate(open_count + 1,close_count,n,current + '(',ans)
        
    #     if close_count < open_count:
    #         self.generate(open_count , close_count + 1, n, current + ')',ans)