[leetcode 32]Longest Valid Parentheses

标签：c++   动规   string   leetcode   

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.

括号匹配，计算最长的括号匹配的字符串，另外如果字符串S1内的括号匹配，字符串s2内的括号匹配，则S1S2应返回s1的长度加s2的长度。

使用栈保存每个字符的下标，进行匹配，计算两下标之间的距离的长度

AC代码

class Solution
{
public:
    int longestValidParentheses(string s)
    {
        int len=s.size();
        stack<int> temp;
        int max=0;
        int count=0;
        for(int i=0; i<len; ++i)
        {
            if(s[i]=='(')
                temp.push(i);
            else
            {
                if(!temp.empty())
                {
                    count=temp.top();
                    if(s[count]==')')
                        temp.push(i);
                    else
                    {
                        temp.pop();
                        if(temp.empty())
                            max=i+1;
                        else
                        {
                            count=temp.top();
                            if(i-count>max)
                                max=i-count;
                        }
                    }

                }
                else
                    temp.push(i);
            }
        }
        return max;
    }
};

[leetcode 32]Longest Valid Parentheses

标签：c++   动规   string   leetcode   

原文地址：http://blog.csdn.net/er_plough/article/details/47183195