题目如下:
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 withB
), whereA
andB
are valid strings, or- It can be written as
(A)
, whereA
is a valid string.Example 1:
Input: s = "lee(t(c)o)de)" Output: "lee(t(c)o)de" Explanation: "lee(t(co)de)" , "lee(t(c)ode)" would also be accepted.Example 2:
Input: s = "a)b(c)d" Output: "ab(c)d"Example 3:
Input: s = "))((" Output: "" Explanation: An empty string is also valid.Example 4:
Input: s = "(a(b(c)d)" Output: "a(b(c)d)"Constraints:
1 <= s.length <= 10^5
s[i]
is one of‘(‘
,‘)‘
and lowercase English letters.
解题思路:本题不难,和以前很多括号问题解法类似。从头开始遍历s,如果为左括号,记录其下标,存入数组 left_unpaired中;如果是右括号,找到与其最近的左括号,并将对应左括号从left_uncompair删除,如果没有最近的括号,将右括号存入 right_unpaired中。最后,只要删掉所有存在于 left_unpaired或 right_unpaired中的括号即可。
代码如下:
class Solution(object): def minRemoveToMakeValid(self, s): """ :type s: str :rtype: str """ left_uncompair = [] left_remove = {} right_remove = {} for i in range(len(s)): if s[i] == ‘(‘: left_uncompair.append(i) left_remove[i] = 1 elif s[i] == ‘)‘: if len(left_uncompair) <= 0: right_remove[i] = 1 else: inx = left_uncompair.pop(-1) del left_remove[inx] res = ‘‘ for i in range(len(s)): if i in right_remove or i in left_remove: continue res += s[i] return res
原文地址:https://www.cnblogs.com/seyjs/p/11790754.html
时间: 2024-11-14 13:38:19