Regular Bracket Sequence

最新推荐文章于 2024-04-22 21:23:46 发布

Scott_Wong06

最新推荐文章于 2024-04-22 21:23:46 发布

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本文探讨了如何从一个包含左括号和右括号的字符串中移除部分字符，以形成最长的有效括号序列。文章提供了一段C++代码示例，用于计算并输出该序列的最大可能长度。

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5637: Regular Bracket Sequence

时间限制: 1 Sec 内存限制: 128 MB
提交: 44 解决: 27
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题目描述

A bracket sequence is called regular if it is possible to obtain correct arithmetic expression by inserting characters «+» and «1» into this sequence. For example, sequences «(())()», «()» and «(()(()))» are regular, while «)(», «(()» and «(()))(» are not.

One day Johnny got bracket sequence. He decided to remove some of the brackets from it in order to obtain a regular bracket sequence. What is the maximum length of a regular bracket sequence which can be obtained?

输入

Input consists of a single line with non-empty string of «(» and «)» characters. Its length does not exceed 10⁶.

输出

Output the maximum possible length of a regular bracket sequence.

样例输入

(()))(

样例输出

#include<cstdio>
#include<cstring>
using namespace std;
const int maxn=1e6+10;
char s[maxn];
int main()
{
    while(scanf("%s",s)!=EOF)
    {
        int len=strlen(s);
        int l=0,r=0;
        for(int i=0;i<len;i++)
        {
            if(s[i]=='(')
                l++;
            if(s[i]==')'&&l>0)
            {
                l--;
                r++;
            }
        }
        printf("%d\n",2*r);
    }
    return 0;
}