集合栈计算机 （The SetStack Computer,ACM/ICPC NWERC 2006,UVa12096

题目描述：

 #include<iostream>
 #include<string>
 #include<set>
 #include<map>
 #include<stack>
 #include<vector>
 #include<algorithm>
 using namespace std;

 #define ALL(x) x.begin(),x.end()
 #define INS(x) inserter(x,x.begin())

 typedef set<int> Set;
 map<Set,int> IDcache; // 把集合映射成ID
 vector<Set> Setcache; // 根据ID取集合

 int ID(Set x){
     if(IDcache.count(x)) return IDcache[x] ;
     Setcache.push_back(x) ;
     return IDcache[x] = Setcache.size() - ;
 }

 int main(){
     int t ;
     cin >> t ;
     while(t--){
         stack<int> s;
         int n;
         cin>> n;
         for(int i=;i<n;i++){
             string op;
             cin >> op;
             if(op[] == 'P') s.push(ID(Set())) ;
             else if (op[] == 'D') s.push(s.top());
             else{
                 Set x1 = Setcache[s.top()] ; s.pop();
                 Set x2 = Setcache[s.top()] ;s.pop() ;
                 Set x ;
                 if (op[] == 'U') set_union (ALL(x1), ALL(x2), INS(x));
                     if (op[] == 'I') set_intersection (ALL(x1), ALL(x2), INS(x));
                 if (op[] == 'A') { x = x2; x.insert(ID(x1)); }
                 s.push(ID(x));
             }
             cout << Setcache[s.top()].size() << endl;
         }
         cout << "***" << endl;
     }
     return ;
 }