UVA 12096 The SetStack Computer 题解

题目链接

UVA 12096: The SetStack Computer

题意

模拟一个存储元素为“集合”的栈操作，对应以下五个命令，分别有五种操作：

• PUSH：空集“{}”入栈
• DUP：把当前栈顶元素复制一份后再入栈
• UNION：出栈两个集合，然后把二者的并集入栈
• INTERSECT：出栈两个集合，然后把二者的交集入栈
• ADD：出栈两个集合，然后把先出栈的集合作为后出栈的集合的元素，加入到第二个集合中，把结果入栈
  每次操作后，输出栈顶集合的大小。

题解

让每一个集合与一个数字一一对应，可以用map< set, int > 和vector< set > 进行快速查找，对于每一个新生成的集合，先在map 中查找之前是否存在，如果不存在，则加入新的集合。

代码

#include <iostream>#include <vector>#include <algorithm>#include <string>#include <set>#include <map>#include <stack>#include <cstdio>#include <list>#include <queue>#include <cstring>using namespace std;#define LL long longvector<set<int> > Vec;map<set<int>, int> Map;stack<int> Sta;vector<int> ans;void Push() {    Sta.push(0);    cout << 0 << endl;}void Dup() {    int tmp = Sta.top();    Sta.push(tmp);    cout << ans[tmp] << endl;}void Union() {    int tmp1 = Sta.top();    Sta.pop();    int tmp2 = Sta.top();    Sta.pop();    set<int> stmp1 = Vec[tmp1];    set<int> stmp2 = Vec[tmp2];    set<int>::iterator it;    for(it = stmp1.begin(); it != stmp1.end(); ++it) {        stmp2.insert(*it);    }    if(Map.find(stmp2) == Map.end()) {        Vec.push_back(stmp2);        Map[stmp2] = Vec.size() - 1;        ans.push_back(stmp2.size());    }    Sta.push(Map[stmp2]);    cout << ans[Map[stmp2]] << endl;}void Intersect(){    int tmp1 = Sta.top();    Sta.pop();    int tmp2 = Sta.top();    Sta.pop();    set<int> stmp1 = Vec[tmp1];    set<int> stmp2 = Vec[tmp2];    set<int> stmp3;    set<int>::iterator it;    for(it = stmp1.begin(); it != stmp1.end(); ++it) {        if(stmp2.find(*it) != stmp2.end()) {            stmp3.insert(*it);        }    }    if(Map.find(stmp3) == Map.end()) {        Vec.push_back(stmp3);        Map[stmp3] = Vec.size() - 1;        ans.push_back(stmp3.size());    }    Sta.push(Map[stmp3]);    cout << ans[Map[stmp3]] << endl;}void Add() {    int tmp1 = Sta.top();    Sta.pop();    int tmp2 = Sta.top();    Sta.pop();    set<int> stmp1 = Vec[tmp1];    set<int> stmp2 = Vec[tmp2];    stmp2.insert(Map[stmp1]);    if(Map.find(stmp2) == Map.end()) {        Vec.push_back(stmp2);        Map[stmp2] = Vec.size() - 1;        ans.push_back(stmp2.size());    }    Sta.push(Map[stmp2]);    cout << ans[Map[stmp2]] << endl;}int main(){    ios::sync_with_stdio(false);    string command;    int T, n;    cin >> T;    while(T--) {        Vec.clear();        Map.clear();        while(!Sta.empty()) Sta.pop();        ans.clear();        Vec.push_back(set<int>());        ans.push_back(0);        Map.insert(pair<set<int>, int>(set<int>(), 0));        cin >> n;        while(n--) {            cin >> command;            switch(command[0]) {            case 'P': Push(); break;            case 'D': Dup(); break;            case 'U': Union(); break;            case 'I': Intersect(); break;            case 'A': Add(); break;            }        }        cout << "***" << endl;    }    return 0;}