题解 | #括号生成#

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param n int整型 
# @return string字符串一维数组
#
class Solution:
    def generateParenthesis(self , n: int) -> List[str]:
        # write code here
        def recursion(left, right, tmp, res, n):
            if left == n and right == n:
                res.append(tmp)
                return

            if left < n:
                recursion(left+1, right, tmp+'(', res, n)
            
            if right < n and left > right:
                recursion(left, right+1, tmp+')', res, n)

        res = []
        tmp = ""
        recursion(0, 0, tmp, res, n)

        return res