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  • Codeforces Round #459 (Div. 2)C. The Monster

    C. The Monster
    time limit per test
    1 second
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    As Will is stuck in the Upside Down, he can still communicate with his mom, Joyce, through the Christmas lights (he can turn them on and off with his mind). He can't directly tell his mom where he is, because the monster that took him to the Upside Down will know and relocate him.

    Thus, he came up with a puzzle to tell his mom his coordinates. His coordinates are the answer to the following problem.

    A string consisting only of parentheses ('(' and ')') is called a bracket sequence. Some bracket sequence are called correct bracket sequences. More formally:

    • Empty string is a correct bracket sequence.
    • if s is a correct bracket sequence, then (s) is also a correct bracket sequence.
    • if s and t are correct bracket sequences, then st (concatenation of s and t) is also a correct bracket sequence.

    A string consisting of parentheses and question marks ('?') is called pretty if and only if there's a way to replace each question mark with either '(' or ')' such that the resulting string is a non-empty correct bracket sequence.

    Will gave his mom a string s consisting of parentheses and question marks (using Morse code through the lights) and his coordinates are the number of pairs of integers (l, r) such that 1 ≤ l ≤ r ≤ |s| and the string slsl + 1... sr is pretty, where si is i-th character of s.

    Joyce doesn't know anything about bracket sequences, so she asked for your help.

    Input

    The first and only line of input contains string s, consisting only of characters '(', ')' and '?' (2 ≤ |s| ≤ 5000).

    Output

    Print the answer to Will's puzzle in the first and only line of output.

    Examples
    input
    ((?))
    
    output
    4
    
    input
    ??()??
    
    output
    7
    
    Note

    For the first sample testcase, the pretty substrings of s are:

    1. "(?" which can be transformed to "()".
    2. "?)" which can be transformed to "()".
    3. "((?)" which can be transformed to "(())".
    4. "(?))" which can be transformed to "(())".

    For the second sample testcase, the pretty substrings of s are:

    1. "??" which can be transformed to "()".
    2. "()".
    3. "??()" which can be transformed to "()()".
    4. "?()?" which can be transformed to "(())".
    5. "??" which can be transformed to "()".
    6. "()??" which can be transformed to "()()".
    7. "??()??" which can be transformed to "()()()".

    
    
    //用r记录到当前位置的"("数量,t记录到当前位置的"?"数量,ans记录匹配数量
    //出现"(",r++
    //出现")",r--
    //出现"?",r--,t++
    
    //if(r==0)刚好匹配 ans++
    //if(r<0&&t>0)  r+=2 t--
    //if(r<0&&t<0)break
    
    
    #include<iostream>
    #include<string>
    #include<fstream>
    using namespace std;
    
    
    int main()
    {
        //freopen("in.txt","r",stdin);
        string str;
        cin>>str;
        int r=0;int t=0;int ans=0;
        for(int j=0;j<str.length();j++)
        {
    
        r=0;t=0;
        for(int i=j;i<str.length();i++)
        {
            if(str[i]=='(')r++;
            else if(str[i]==')')r--;
            else r--,t++;
            if(r==0)ans++;
            else if(r<0&&t>0)r+=2,t--;
            else if(r>0) continue;
            else if(r<0&&!t)break;
    
        }
        }
        cout<<ans<<endl;
    
    
        return 0;
    }
    





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  • 原文地址:https://www.cnblogs.com/bryce1010/p/9387021.html
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