UVA 673 Parentheses Balance

1.题目是栈的简单应用，但是由于其特殊的条件性，使得空字符串也满足条件，所以也带来了不少的麻烦

2.两种字符要放到同一个栈中去判断，也就是【（】）这种情况是错误的。。第一次由于没有注意到这一点导致WA了很久，

3.下面附上代码：

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <string>
#include <stack>
using namespace std;
int main()
{
    int T;char sign;
    cin>>T;
    cin.get();
    while(T--)
    {
        string s="";
        stack<char> one;
        one.push('#');
        bool flag=true;
        if((sign=cin.get())=='\n')
            printf("Yes\n");
        else
        {
            s=sign+s;
            while((sign=cin.get())!='\n')
                s=s+sign;
            //cout<<s<<endl;
            for(int i=0;i<s.length();i++)
            {

                if(s.at(i)=='(')
                    one.push('(');
                else if(s.at(i)=='['){
                    one.push('[');
                }

                else if(s.at(i)==')')
                {
                    if(one.top()=='(')
                        one.pop();
                    else{

                        flag=false;break;
                    }

                }
                else if(s.at(i)==']')
                {
                    if(one.top()=='[')
                        one.pop();
                    else{
                        flag=false;break;
                    }
                }
            }
            //cout<<one.top()<<endl;
            if(one.top()!='#')
                flag=false;
            if(flag)
                printf("Yes\n");
            else
                printf("No\n");
        }
    }
    //system("pause");
    return 0;
}