[LeetCode]Longest Valid Parentheses

标签：括号配对

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.

自己没写对，看的网上的资料：

这道题时间限制在O(n)，用一个 stack 实现括号配对+统计, 为了方便实现，写成数组的形式。

对不同深度的括号配对统计个数，一层配对成功把该层统计结果加给上一层，这一层清空

class Solution {
public:
    int longestValidParentheses(string s) {
   int ans = 0;
	std::vector<int> count(1, 0);
	for (int i = 0;  i < s.size(); i++)
	{
		if (s[i] == '(')
		{
			count.push_back(0);
		}
		else
		{
			if (count.size() > 1)
			{
				count[count.size() - 2] += *count.rbegin() + 2;
				count.pop_back();
				ans = ans > *count.rbegin() ? ans : *count.rbegin();
			}
			else
			{
				count[0] = 0;
			}
		}
	}
	return ans;
    }
};

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[LeetCode]Longest Valid Parentheses

标签：括号配对

原文地址：http://blog.csdn.net/jet_yingjia/article/details/27214407