栈的应用uva673

#include<iostream>
#include<stack>
#include<string>
#include<cstdio>
using namespace std;
int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
    #endif

    int t;
    cin>>t;
    getchar();
    while(t--)
    {
        stack<char> s;
        string a;
        getline(cin,a);
        bool flag=true;
        for(int i=0;i<a.size();i++)
        {
            if(s.empty()){s.push(a[i]);continue;}
            if(a[i]=='[')s.push(a[i]);
            else if(a[i]==']')
            {
                if(s.top()!='['){s.push(a[i]);}
                else s.pop();
            }
            else if(a[i]=='(')s.push(a[i]);
            else if(a[i]==')')
            {
                if(s.top()!='('){s.push(a[i]);}
                else s.pop();
            }
        }
        if(!s.empty())flag=false;
        if(flag)cout<<"Yes"<<endl;
        else cout<<"No"<<endl;
    }
    return 0;
}