oj 括号字符串匹配问题（栈）

#include<iostream>#include<string>#include<stack>using namespace std;int main(){string str;int n=0;cin>>n;for(int i=0;i<n;i++){stack<char> small;int flag=0;cin>>str;for(int j=0;j<str.size();j++){switch(str[j]){case '(': small.push(str[j]);break;case ')': if(!small.empty()){small.pop();break;  }  if(small.empty()) { flag=1;  break;  }}}if(small.empty()&&flag==0) cout<<"TRUE"<<endl;else cout<<"FALSE"<<endl;}return 0;}