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)" 分析:用一个stack来记录需要删除的括号,最后把它们删除了就可以了。
1 class Solution { 2 public String minRemoveToMakeValid(String s) { 3 StringBuilder sb = new StringBuilder(s); 4 Stack<Integer> st = new Stack(); 5 for (int i = 0; i < sb.length(); ++i) { 6 if (sb.charAt(i) == ‘(‘) { 7 st.add(i + 1); 8 } else if (sb.charAt(i) == ‘)‘) { 9 if (!st.empty() && st.peek() > 0) { 10 st.pop(); 11 } else { 12 st.add(-(i + 1)); 13 } 14 } 15 } 16 while (!st.empty()) { 17 sb.deleteCharAt(Math.abs(st.pop()) - 1); 18 } 19 return sb.toString(); 20 } 21 }
原文地址:https://www.cnblogs.com/beiyeqingteng/p/12268458.html
时间: 2024-11-15 00:53:22