UVA - 12096 The SetStack Computer

对于每个操作, 输出栈顶集合 A 中的元素个数.

思路：STL的各种应用，注意Add的时候要注意，本来判断是否出现这个集合，没有的话， 才设置一个唯一值再加入集合，但是这样不对，不管是否出现都加入才对

#include <iostream>
#include <cstdio>
#include <cstring>
#include <stack>
#include <map>
#include <set>
using namespace std;
const int MAXN = 2010;
const int N = 20;

int cnt;
stack<set<int> > stk;
map<set<int>, int> mp;
set<int> s1,s2;

void pop(){
    s1 = stk.top();
    stk.pop();
    s2 = stk.top();
    stk.pop();
}

void Push(){
    set<int> s;
    stk.push(s);
    printf("0\n");
}

void Dup(){
    set<int> s;
    s = stk.top();
    stk.push(s);
    printf("%d\n",s.size());
}

void Union(){
    pop();
    set<int>::iterator it;
    for (it = s1.begin(); it != s1.end(); it++)
        s2.insert(*it);
    stk.push(s2);
    printf("%d\n",s2.size());
}

void Intersect(){
    pop();
    set<int> s3;
    set<int>::iterator it;
    for (it = s1.begin(); it != s1.end(); it++)
        if (s2.find(*it) != s2.end())
            s3.insert(*it);
    stk.push(s3);
    printf("%d\n",s3.size());
}

void Add(){
    pop();
    if (s1.empty())
        s2.insert(0);
    else {
        if (!mp[s1])
            mp[s1] = cnt++;
        s2.insert(mp[s1]);
    }
    stk.push(s2);
    printf("%d\n",s2.size());
}

int main(){
    int t,n;
    char str[N];
    scanf("%d",&t);
    while (t--){
        scanf("%d",&n);
        while (!stk.empty())
            stk.pop();
        cnt = MAXN;
        mp.clear();
        while (n--){
            scanf("%s",str);
            if (str[0] == ‘P‘)
                Push();
            else if (str[0] == ‘D‘)
                Dup();
            else if (str[0] == ‘U‘)
                Union();
            else if (str[0] == ‘I‘)
                Intersect();
            else Add();
        }
        printf("***\n");
    }
    return 0;
}

UVA - 12096 The SetStack Computer

原文：http://blog.csdn.net/u011345136/article/details/19707183