SetStack.cpp

#include <iostream>
#include <map>
#include <set>
#include <vector>
#include <stack>
using namespace std;
typedef set<int>Set;
map<Set,int>IDcache;
vector<Set> Setcache; 
//查找给定集合x的ID。如果找不到，分配一个新ID
int ID(Set s){
    if(IDcache.count(s)) return IDcache[s];
    Setcache.push_back(s);
    return IDcache[s]=Setcache.size()-1;
}

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

int main(){
    stack <int>s;
    int n;
    cin>>n;
    for(int i=0;i<n;i++){
        string op;
        cin>>op;
        if(op[0]=='P') s.push(ID(Set()));
        else if(op[0]=='D') s.push(s.top());
        else{
            Set x1=Setcache[s.top()];s.pop();
            Set x2=Setcache[s.top()];s.pop();
            Set x;
            if(op[0]=='U'); //set_union(ALL(x1),ALL(x2),INS(x));
            if(op[0]=='I'); //set_intersection(ALL(x1),ALL(x2),INS(x));
            if(op[0]=='A') {x=x2;x.insert(ID(x1));}
            s.push(ID(x));
        }
    cout<<Setcache[s.top()].size()<<endl;
    }
    return 0;
}