leetcode Ch2-Dynamic Programming II

一、 Longest Valid Parentheses

方法一、一维DP

 1 class Solution
 2 {
 3 public:
 4     int longestValidParentheses(string s)
 5     {
 6         vector<int> dp(s.size(),0);
 7         int res=0;
 8         for(int i=s.size()-2;i>=0;i--)
 9         {
10             if(s[i]==')')
11                 dp[i]=0;
12             else
13             {
14                 int j=i+dp[i+1]+1;
15                 if(j<s.size()&&s[j]==')')
16                 {
17                     dp[i]+=dp[i+1]+2;
18                     if(j+1<s.size())
19                         dp[i]+=dp[j+1];
20                 }
21             }
22             res=max(res,dp[i]);
23         }
24         return res;
25     }
26 };

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