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Given a string containing just the characters ‘(‘ and ‘)‘, find the length of the longest valid (well-formed) parentheses substring.
For "(()", the longest valid parentheses substring is "()", which has length = 2.
Another example is ")()())", where the longest valid parentheses substring is "()()", which has length = 4.
1 class Solution { 2 public: 3 int longestValidParentheses(string s) { 4 int n=s.length(); 5 if(n==0) return 0; 6 7 int *dp=new int[n]; 8 dp[n-1]=0; 9 10 int result=0; 11 for(int i=n-2;i>=0;i--) 12 { 13 if(s[i]==‘(‘) 14 { 15 int j=dp[i+1]+i+1; 16 17 if(s[j]==‘)‘) 18 { 19 dp[i]=dp[i+1]+2; 20 if(j<n-1) dp[i]+=dp[j+1]; 21 } 22 else 23 { 24 dp[i]=0; 25 } 26 27 if(dp[i]>result) 28 { 29 result=dp[i]; 30 } 31 } 32 else 33 { 34 dp[i]=0; 35 } 36 } 37 delete [] dp; 38 return result; 39 } 40 };
【leetcode】Longest Valid Parentheses
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原文地址：http://www.cnblogs.com/reachteam/p/4199945.html
