[leetcode 32] Longest Valid Parentheses

最长有效括号子串

最新推荐文章于 2025-09-10 15:24:29 发布

转载最新推荐文章于 2025-09-10 15:24:29 发布 · 44 阅读

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原文链接：http://www.cnblogs.com/ym65536/p/4273515.html

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#数据结构与算法

本文介绍了一种使用bool数组记录可成对括号位置的方法，并通过动态规划求解字符串中最大有效括号子串的长度。举例说明了如何处理如(()和)()())等输入。

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.

[Solution]

用bool数组记录可以组成成对括号的位置，再用动态规划求解最大连续的true的个数。

 1 int longestValidParentheses(string s) 
 2     {
 3         stack<int> leftPos;
 4         vector<bool> table(s.size(), false);
 5         int global_max = 0, suffix_max = 0;
 6         
 7         for (int i = 0; i < s.size(); i++)
 8         {
 9             if (s[i] == '(')
10                 leftPos.push(i);
11             else if (!leftPos.empty())
12             {
13                 table[i] = true;
14                 table[leftPos.top()] = true;
15                 leftPos.pop();
16             }
17         }
18         
19         for (int i = 0; i < table.size(); i++)
20         {
21             if (table[i] == true)
22                 suffix_max++;
23             else
24                 suffix_max = 0;
25             if (global_max < suffix_max)
26                 global_max = suffix_max;
27         }
28         
29         return global_max;
30     }