如何检查两个std :: vector是否只包含相同的元素？

Question

我需要一个算法或标准库函数来比较两个向量元素,如下所示:

class Utility
{
    template <class T>
    static bool CheckIfVectorsEquivalent(   const std::vector<T> & Vec1,
                                            const std::vector<T> & Vec2)
    {
        // ???
    }
};

按照以下规格工作:

std::vector<int> v1, v2, v3, v4, v5, v6, v7, v8;

// Returns false when not all the elements are matching between vectors
v1.push_back(1);
v1.push_back(3);
v1.push_back(5);
v2.push_back(2);
v2.push_back(3);
v2.push_back(8);
Utility::CheckIfVectorsEquivalent(v1, v2);  // Must return false

// Returns true when all the elements match, even if the are not in the same order
v3.push_back(3);
v3.push_back(1);
v3.push_back(7);
v4.push_back(7);
v4.push_back(3);
v4.push_back(1);
Utility::CheckIfVectorsEquivalent(v3, v4);  // Must return true

// Returns false when one of the vectors is subset of the other one
v5.push_back(3);
v5.push_back(1);
v5.push_back(7);
v6.push_back(7);
v6.push_back(3);
v6.push_back(1);
v6.push_back(18);
v6.push_back(51);
Utility::CheckIfVectorsEquivalent(v5, v6);  // Must return false

// Returns true when the both vectors are empty
Utility::CheckIfVectorsEquivalent(v7, v8);  // Must return true

有没有标准(用STL)这样做的方法？如果没有,我该怎么写这个算法？这让我很困惑.

Answer 1

标准方法是对这两个向量==进行排序并使用运算符,该运算符比较相应的值.

实现此算法的示例解决方案是:

#include <vector>
#include <algorithm>

template<typename T>
bool compare(std::vector<T>& v1, std::vector<T>& v2)
{
    std::sort(v1.begin(), v1.end());
    std::sort(v2.begin(), v2.end());
    return v1 == v2;
}

由于排序,其复杂度为O(n*log(n)).

Answer 2

如果您只能使用c ++ 11解决方案,那么std::is_permutation这正是您想要的

template <class FI1, class FI2>
bool is_permutation ( FI1 first, FI1 last, FI2 d_first );

如果你不能那样做,那么在即将推出的1.50版本中,将会有

boost::algorithm::is_permutation

具有相同的界面.