編程第六十三、六十四天

c++ algorithm set方法

#include <iostream>
#include <set>
#include <algorithm>
#include <iterator>
using namespace std;

template <class T>
struct display
{
    void operator()(const T &x)
    {
        cout<<x<<" ";
    }

};
int main()
{
    int ia1[]={1,3,5,7,9,11};
    int ia2[]={1,1,2,3,5,8,13};

    multiset<int> s1(ia1,ia1+6);
    multiset<int> s2(ia2,ia2+7);
    for_each(s1.begin(),s1.end(),display<int>());
    cout<<endl;
    for_each(s2.begin(),s2.end(),display<int>());
    cout<<endl;

    multiset<int>::iterator first1 = s1.begin();
    multiset<int>::iterator last1 = s1.end();
    multiset<int>::iterator first2 = s2.begin();
    multiset<int>::iterator last2 = s2.end();

    cout<<"union of s1 and s2: ";
    //兩個集合合併，相同元素個數取 max(m,n)。
    set_union(first1,last1,first2,last2,ostream_iterator<int>(cout," "));
    cout<<endl;

    first1=s1.begin();
    first2=s2.begin();
    cout<<"Intersection of s1 and s2: ";
    //兩個集合交集，相同元素個數取 min(m,n).
    set_intersection(first1,last1,first2,last2,ostream_iterator<int>(cout," "));
    cout<<endl;

    first1=s1.begin();
    first2=s2.begin();
    cout<<"Intersection of s1 and s2: ";
    //兩個集合差集 就是去掉S1中 的s2
    set_difference(first1,last1,first2,last2,ostream_iterator<int>(cout," "));
    cout<<endl;

    first1=s1.begin();
    first2=s2.begin();
    cout<<"Intersection of s1 and s2: ";
    //兩個集合對稱差集：就是取兩個集合互相沒有的元素 。兩個排序區間，元素相等指針後移，不等輸出小的並前進
    //相同元素的個數 abs(m-n)
    set_symmetric_difference(first1,last1,first2,last2,ostream_iterator<int>(cout," "));
    cout<<endl;


    return 0;
}