力扣 22. 括号生成 python AC

递归

class Solution:
    def __init__(self):
        self.n = None
        self.str = []
        self.res = []

    def judge(self):
        if self.str.count('(') == self.str.count(')') == self.n:
            ll = []
            for i in self.str:
                if i == '(':
                    if ')' not in ll:
                        ll.append('(')
                    else:
                        return False
                else:
                    if '(' not in ll:
                        return False
                    else:
                        ll.remove('(')
            return True
        return False

    def dfs(self):
        if self.judge():
            self.res.append(''.join(i for i in self.str))
            return
        if len(self.str) > 2 * self.n:
            return
        self.str.append('(')
        self.dfs()
        self.str.pop(-1)
        self.str.append(')')
        self.dfs()
        self.str.pop(-1)

    def generateParenthesis(self, n):
        self.n = n
        self.dfs()
        return self.res


a = Solution()
print(a.generateParenthesis(3))