C++ set_intersection

原文
求交集
set_union是求并集
用法类似

// set_intersection example
#include <iostream> // std::cout
#include <algorithm> // std::set_intersection, std::sort
#include <vector> // std::vector
using namespace std;
int main ()
{
  int first[] = {5,10,15,20,25};
  int second[] = {50,40,30,20,10};
  vector<int> v(10);                      // 0 0 0 0 0 0 0 0 0 0
  vector<int>::iterator it;
  sort (first,first+5);     // 5 10 15 20 25
  sort (second,second+5);   // 10 20 30 40 50
  it = set_intersection (first, first+5, second, second+5, v.begin()); // 10 20 0 0 0 0 0 0 0 0
  v.resize(it -v.begin());                      // 10 20
  cout << "The intersection has " << (v.size()) << " elements:\n";
  for (it=v.begin(); it!=v.end(); ++it)
    cout << ' ' << *it;
  cout << '\n';
  return 0;
}