STL algorithm set_symmetric_difference, set_union (54)

Set_effecric_difference prototype:

STD: set_policric_difference

Default (1)	template <class InputIterator1, class InputIterator2, class OutputIterator> OutputIterator set_symmetric_difference (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result);
Custom (2)	template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare> OutputIterator set_symmetric_difference (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);

This function is used to calculate the symmetry difference between two sets.

The pre-use sequence should be ordered.

The concept of Symmetric Difference is:

Mathematical terms in set theory, that is, the symmetry difference between two sets is a set composed of only one, not the elements of the other. This operation in set theory is equivalent to the XOR operation in Boolean logic. The symmetry difference between A and B is usually expressed as a △b. For example, the symmetry difference between {1, 2, 3} and {3, 4} In a set is {1, 2, 4 }. The symmetry difference between a set of all students and a set of all female students is a set of all malsexual students and all female non-students. It indicates that the symbol is △or △. The symmetry difference is equivalent to the union of two relative complementary sets, namely:

Symmetric Difference the Wen's diagram represents, and the red area represents the Symmetric Difference

A Delta B = (? B) round (B? A) can also be expressed as the union of two sets minus their intersection: A △b = (A then B )? (A branch B) -- from Baidu encyclopedia

The behavior is similar:

template <class InputIterator1, class InputIterator2, class OutputIterator>  OutputIterator set_symmetric_difference (InputIterator1 first1, InputIterator1 last1,                                           InputIterator2 first2, InputIterator2 last2,                                           OutputIterator result){  while (true)  {    if (first1==last1) return std::copy(first2,last2,result);    if (first2==last2) return std::copy(first1,last1,result);    if (*first1<*first2) { *result=*first1; ++result; ++first1; }    else if (*first2<*first1) { *result = *first2; ++result; ++first2; }    else { ++first1; ++first2; }  }}

A simple example:

#include <iostream>#include <algorithm>#include <vector>using namespace std;void setsydifference(){    vector<int> vi{1,2,3,4,4,6,9,22,11};    vector<int> v2{1,2,3,5,4,9,8};    vector<int> vresult(10);    sort(vi.begin(),vi.end());    sort(v2.begin(),v2.end());    cout<<"vi=";    for(int i:vi)        cout<<i<<" ";    cout<<endl;    cout<<"v2=";    for(int i:v2)        cout<<i<<" ";    cout<<endl;    auto it=set_symmetric_difference(vi.begin(),vi.end(),v2.begin(),v2.end(),vresult.begin());    cout<<"vreult=";    for(auto i=vresult.begin();i!=it;++i)        cout<<*i<<" ";    cout<<endl;}

Run:

Set_union prototype:

STD: set_union

Default (1)	template <class InputIterator1, class InputIterator2, class OutputIterator> OutputIterator set_union (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result);
Custom (2)	template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare> OutputIterator set_union (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);

This function is used to obtain the union of two sets.

The pre-use sequence should be in ascending order.

The behavior is similar:

template <class InputIterator1, class InputIterator2, class OutputIterator>  OutputIterator set_union (InputIterator1 first1, InputIterator1 last1,                            InputIterator2 first2, InputIterator2 last2,                            OutputIterator result){  while (true)  {    if (first1==last1) return std::copy(first2,last2,result);    if (first2==last2) return std::copy(first1,last1,result);    if (*first1<*first2) { *result = *first1; ++first1; }    else if (*first2<*first1) { *result = *first2; ++first2; }    else { *result = *first1; ++first1; ++first2; }    ++result;  }}

A simple example:

#include <iostream>#include <algorithm>#include <vector>using namespace std;void setunion(){    vector<int> vi{1,2,3,4,4,6,9,22,11};    vector<int> v2{1,2,3,5,4,9,8};    vector<int> vresult(15);    sort(vi.begin(),vi.end());    sort(v2.begin(),v2.end());    cout<<"vi=";    for(int i:vi)        cout<<i<<" ";    cout<<endl;    cout<<"v2=";    for(int i:v2)        cout<<i<<" ";    cout<<endl;    auto it=set_union(vi.begin(),vi.end(),v2.begin(),v2.end(),vresult.begin());    cout<<"vreult=";    for(auto i=vresult.begin();i!=it;++i)        cout<<*i<<" ";    cout<<endl;}

Run:

------------------------------------------------------------------

// For more instructions on writing errors or poor information, you can leave a message below or click the email address in the upper left corner to send an email to me, pointing out my errors and deficiencies, so that I can modify them, thank you for sharing it.

Reprinted please indicate the source: http://blog.csdn.net/qq844352155

Author: unparalleled

Email: [email protected]

Yu gdut

--------------------------------------------------

STL algorithm set_symmetric_difference, set_union (54)