c++ - C++中的 vector 交集

Question

我有这个功能

vector<string> instersection(const vector<string> &v1, const vector<string> &v2);

我有两个字符串 vector ，我想找到两者中都存在的字符串，然后用公共(public)元素填充第三个 vector 。

如果我的 vector 是...

v1 = <"a","b","c">
v2 = <"b","c">

Answer 1

试试 std::set_intersection ，例如:

#include <algorithm> //std::sort
#include <iostream> //std::cout
#include <string> //std::string
#include <vector> //std::vector

std::vector<std::string> intersection(std::vector<std::string> v1,
                                      std::vector<std::string> v2){
    std::vector<std::string> v3;

    std::sort(v1.begin(), v1.end());
    std::sort(v2.begin(), v2.end());

    std::set_intersection(v1.begin(),v1.end(),
                          v2.begin(),v2.end(),
                          back_inserter(v3));
    return v3;
}

int main(){
    std::vector<std::string> v1 {"a","b","c"};
    std::vector<std::string> v2 {"b","c"};

    auto v3 = intersection(v1, v2);

    for(std::string n : v3)
        std::cout << n << ' ';
}