【Uva 12096】The SetStack Computer

这道题能在《算法经典（第二版）》上找到，不贴图了。

看了看书，发现书比我自己想到的好多了。

苟蒻在此跪拜 刘汝佳大神。

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<set>
#include<map>
#include<vector>
#include<stack>
#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> idcard;
vector<Set> setid;
stack<int> s;
int n;

int get_id(Set x)
{
    if (idcard.count(x)) return idcard[x];
    setid.push_back(x);
    return idcard[x] = setid.size() - 1;
}

int main()
{
    int Test;
    scanf("%d", &Test);
    while (Test--)
    {
        scanf("%d", &n);
        while (!s.empty()) s.pop();
        setid.clear();
        idcard.clear();
        while (n--)
        {
            char cmd[10];
            scanf("%s", &cmd);
            if (cmd[0] == 'P') s.push(get_id(Set()));
            else if (cmd[0] == 'D') s.push(s.top());
                else
                {
                    Set x1 = setid[s.top()];
                    s.pop();
                    Set x2 = setid[s.top()];
                    s.pop();
                    Set x;
                    if (cmd[0] == 'U') set_union(ALL(x1), ALL(x2), INS(x));
                    if (cmd[0] == 'I') set_intersection(ALL(x1), ALL(x2), INS(x));
                    if (cmd[0] == 'A') {
                        x = x2;
                        x.insert(get_id(x1));
                    }
                    s.push(get_id(x));
                }
            printf("%d\n", setid[s.top()].size());
        }
        printf("***\n");
    }
    return 0;
}