标签：col 字符串 i++ output char lan nbsp show 左右
Given a string containing just the characters ‘(‘ and ‘)‘, find the length of the longest valid (well-formed) parentheses substring.
Example 1:
Input: "(()"
Output: 2
Explanation: The longest valid parentheses substring is "()"
Example 2:
Input: ")()())"
Output: 4
Explanation: The longest valid parentheses substring is "()()"
找最长的合法左右括号字符串
这道题还蛮难的，一开始我的dp思路错误了（n3的复杂度真是不像话）
把dp数组设为以当前索引值为末尾的合法字符串的长度就可以做了
1 class Solution { 2 public: 3 int longestValidParentheses(string s) { 4 int l = s.length(); 5 if (l < 2)return 0; 6 int ans = 0; 7 vector<int>dp; 8 dp.resize(l); 9 for (int i = 0; i < l; i++) 10 dp[i] = 0; 11 if (s[0] == ‘(‘&&s[1] == ‘)‘) { 12 ans = 2; 13 dp[1] = 2; 14 } 15 for (int i = 2; i < l; i++) { 16 if (s[i] == ‘(‘)continue; 17 if (s[i - 1] == ‘(‘)dp[i] = dp[i - 2] + 2; 18 else { 19 int last = dp[i - 1]; 20 if (i - last - 1 >= 0 && s[i - last - 1] == ‘(‘) { 21 dp[i] = last + 2; 22 if (i - last - 2 >= 0) 23 dp[i] += dp[i - last - 2]; 24 } 25 } 26 ans = max(ans, dp[i]); 27 } 28 return ans; 29 } 30 };
19.2.1 [LeetCode 32] Longest Valid Parentheses
标签：col 字符串 i++ output char lan nbsp show 左右
原文地址：https://www.cnblogs.com/yalphait/p/10346751.html
