LeetCode 1249. Minimum Remove to Make Valid Parentheses解题报告(python)

1249. Minimum Remove to Make Valid Parentheses

1249. Minimum Remove to Make Valid Parentheses python solution

题目描述

Given a string s of ‘(’ , ‘)’ and lowercase English characters.
Your task is to remove the minimum number of parentheses ( ‘(’ or ‘)’, in any positions ) so that the resulting parentheses string is valid and return any valid string.
Formally, a parentheses string is valid if and only if:
It is the empty string, contains only lowercase characters, or
It can be written as AB (A concatenated with B), where A and B are valid strings, or
It can be written as (A), where A is a valid string.

解析

之前做过类似的题目，就是配对"(“和“)”。而且必须”("在“)”的前面出现。
需要对所有的括号进行判断，只有有效的括号才能被保留。

class Solution:
    def minRemoveToMakeValid(self, s: str) -> str:
        stack=[]
        state_dict={}
        for idx, character in enumerate(s):
            if character=="(":
                stack.append(idx)
            if character==")" and len(stack)>0 :
                state_dict[idx]=True
                state_dict[stack[-1]]=True
                stack.pop()
                
        res=[]
        for idx, ch in enumerate(s):
            if ch=="(" or ch== ")":
                if idx in state_dict:res.append(ch)
            else:res.append(ch)
        
        return res
                

Reference

https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/discuss/419880/Simply-Simple-Python-Solution-with-comments