括号配对问题

描述现在，有一行括号序列，请你检查这行括号是否配对。

 

输入

第一行输入一个数N（0<N<=100）,表示有N组测试数据。后面的N行输入多组输入数据，每组输入数据都是一个字符串S(S的长度小于10000，且S不是空串），测试数据组数少于5组。数据保证S中只含有"[","]","(",")"四种字符

输出

每组输入数据的输出占一行，如果该字符串中所含的括号是配对的，则输出Yes,如果不配对则输出No

#include<iostream>
#include<stack>
#include<string>
using namespace std;
int main()
{
    stack<char> q;
    int N,i,len,flag;
    string str;
    cin>>N;
    while(N--)
    {
        cin>>str;
        flag=1;
        while(!q.empty())
        q.pop();
        len=str.length();
        for(i=0;i<len;++i)
        {
            if(q.empty())
            {
                if(str[i]==']'||str[i]==')')
                {
                    flag=0;
                    break;
                }
                else
                q.push(str[i]);
            }
            else
            {
                if(q.top()=='[')
                {
                    if(str[i]==']')
                    q.pop();
                    else if(str[i]==')')
                    {
                        flag=0;
                        break;
                    }
                    else if(str[i]=='('||str[i]=='[')
                    q.push(str[i]);
                }
                else if(q.top()=='(')
                {
                    if(str[i]==')')
                    q.pop();
                    else if(str[i]==']')
                    {
                        flag=0;
                        break;
                    }
                    else if(str[i]=='('||str[i]=='[')
                    q.push(str[i]);
                }
            }
        }
        if(flag)
        cout<<"Yes"<<endl;
        else
        cout<<"No"<<endl;
    }
}