C++ set_union

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原文

set_union可以合并两个排好序的区域成一个set
i.e. 去重
it = set_union(first, first + 5, second, second + 5, v.begin());
first, second都是数组，并且排好序了
v 是 vector，把集合生成到 v里去
然后返回生成集合末尾的迭代器 it

// set_union example#include <iostream>     // std::cout#include <algorithm>    // std::set_union, std::sort#include <vector>       // std::vectorusing 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_union(first, first + 5, second, second + 5, v.begin());  // 5 10 15 20 25 30 40 50  0  0  v.resize(it - v.begin());  // 5 10 15 20 25 30 40 50  cout << "The union has " << (v.size()) << " elements:\n";  for (it = v.begin(); it != v.end(); ++it)    cout << ' ' << *it;  cout << '\n';  return 0;}

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