仅使用重复项从其他人创建新载体 [英] Create new vector from others, using only duplicates

问题描述

比方说我有一组 vector< int> ：

std::vector<int> a = {2,3,8,4,9,0,6,10,5,7,1};
std::vector<int> b = {6,10,8,2,4,0};
std::vector<int> c = {0,1,2,4,5,8};

我想创建一个新向量，使所有输入都只有相同的元素向量被输入到新向量中，如下所示：

I want to create a new vector, in such a way that only elements which are common to all input vectors are input into the new vector as follows:

std::vector<int> abc = {8,2,0,8}; // possible output, order doesn't matter

我看到很多问题询问如何删除重复项，但我希望仅保留 重复项。

I have seen many questions asking for how to remove duplicates, but I wish to retain only duplicates.

是否存在现有的有效STL算法或结构可以

Is there an existing efficient STL algorithm or construct that will do this for me, or do I need to write my own?

推荐答案

如上所述，您可以使用算法 set_intersection 即可：
但是您还必须对<$ c $进行排序c> vector 第一个

As mentioned, you can use an algorithm set_intersection to do this: But you will also have to sort the vectors first

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
int main()
{
    std::vector<int> a = {0,1,2,3,4,5,6,7,8,9,10};
    std::vector<int> b = {0,2,4,6,8,10};
    std::vector<int> c = {0,1,2,4,5,8};

    std::vector<int> temp;
    std::vector<int> abc;

    std::sort(a.begin(), a.end());
    std::sort(b.begin(), b.end());
    std::sort(c.begin(), c.end());

    std::set_intersection(a.begin(), a.end(),
                          b.begin(), b.end(),
                          std::back_inserter(temp));

    std::set_intersection(temp.begin(), temp.end(),
                          c.begin(), c.end(),
                          std::back_inserter(abc));

    for(int n : abc)
        std::cout << n << ' ';
}

实时演示

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