STL 之includes,set_intersection,set_union,set_difference,set_symmetric

includes,set_intersection,set_union,set_difference,set_symmetric_difference都是集合论中的操作。这些算法都假定指定区间类的元素已经有序。

includes：A∈B

set_intersection：A∩B

set_union：A∪B

set_difference：A-B

set_symmetric_difference：（A-B）∪（B-A）

1，includes

声明：

#include <algorithm>
template <class inputItr1, class inputItr2>
bool includes(inputItr1 first1, inputItr1 last1, inputItr2 first2, inputItr2 last2);
template <class inputItr1, class inputItr2, class binaryPredicate>
bool includes(inputItr1 first1, inputItr1 last1, inputItr2,binaryPredicate op);

示例代码：

#include <iostream>
#include <list>
#include <string>
#include <numeric>
#include <iterator>
#include <vector>
#include <functional>
#include <algorithm>
using namespace std;
int main() {
char setA[5] = {'A','B','C','D','E'};
char setB[10] = {'A','B','C','D','E','F','I','J','K','L'};
char setC[5] = {'A','E','I','O','U'};
ostream_iterator<char> screen(cout, " ");
cout << "setA:" << endl;
copy(setA,setA+5,screen);
cout << endl;
cout << "setB:" << endl;
copy(setB,setB+10,screen);
cout << endl;
cout << "setC:" << endl;
copy(setC,setC+5,screen);
cout << endl;
if (includes(setB,setB+10,setA,setA+5))
{
cout << "setA is a subset of setB" << endl;
} else {
cout << "setA is not a subset of setB" << endl;
}
if (includes(setB,setB+10,setC,setC+5))
{
cout << "setC is a subset of setB" << endl;
} else {
cout << "setC is not a subset of setB" << endl;
}
return 0;
}

运行结果：

charList:
a b c d e
charList:
A B C D E
list
2 8 5 1 7 11 3
4 16 10 2 14 22 6
list
4 16 10 2 14 22 6

2，set_intersection,set_union

声明：

#include <algorithm>
template <class inputItr1, class inputItr2,class outputItr>
outputItr set_intersection(inputItr1 first1, inputItr1 last1, inputItr2 first2,inputItr2 last2,outputItr destFirst);
template <class inputItr1, class inputItr2,class outputItr,class binaryPredicate>
outputItr set_intersection(inputItr1 first1, inputItr1 last1, inputItr2 first2,inputItr2 last2,outputItr destFirst,binaryPredicate op);
template <class inputItr1, class inputItr2,class outputItr>
outputItr set_union(inputItr1 first1, inputItr1 last1, inputItr2 first2,inputItr2 last2,outputItr destFirst);
template <class inputItr1, class inputItr2,class outputItr,class binaryPredicate>
outputItr set_union(inputItr1 first1, inputItr1 last1, inputItr2 first2,inputItr2 last2,outputItr destFirst,binaryPredicate op);

示例代码：

#include <iostream>
#include <list>
#include <string>
#include <numeric>
#include <iterator>
#include <vector>
#include <functional>
#include <algorithm>
using namespace std;
int main() {
int setA[5] = {2,4,5,7,8};
int setB[7] = {1,2,3,4,5,6,7};
int setC[5] = {2,5,8,8,15};
int setD[6] = {1,4,4,6,7,12};
int AunionB[10];
int AunionC[10];
int BunionD[15];
int AintersectB[10];
int AintersectC[10];
int * lastElement;
ostream_iterator<int> screen(cout," ");
cout << "setA:" << endl;
copy(setA,setA+5,screen);
cout << endl;
cout << "setB:" << endl;
copy(setB,setB+7,screen);
cout << endl;
cout << "setC:" << endl;
copy(setC,setC+5,screen);
cout << endl;
cout << "setD:" << endl;
copy(setD,setD+6,screen);
cout << endl;
// set_union
lastElement = set_union(setA,setA+5,setB,setB+7,AunionB);
cout << "AunionB:" << endl;
copy(AunionB,lastElement,screen);
cout << endl;
lastElement = set_union(setA,setA+5,setC,setC+5,AunionC);
cout << "AunionC:" << endl;
copy(AunionC,lastElement,screen);
cout << endl;
lastElement = set_union(setB,setB+7,setD,setD+6,BunionD);
cout << "BunionD:" << endl;
copy(BunionD,lastElement,screen);
cout << endl;
// set_intersection
lastElement = set_intersection(setA, setA+5,setB,setB+7,AintersectB);
cout << "AintersectB:" << endl;
copy(AintersectB,lastElement,screen);
cout << endl;
lastElement = set_intersection(setA, setA+5,setC,setC+5,AintersectC);
cout << "AintersectC:" << endl;
copy(AintersectC,lastElement,screen);
cout << endl;
return 0;
}

运行结果：

charList:
a b c d e
charList:
A B C D E
list
2 8 5 1 7 11 3
4 16 10 2 14 22 6
list
4 16 10 2 14 22 6

3 set_difference,set_symmetric_difference

声明：

#include <algorithm>
template <class inputItr1, class inputItr2,class outputItr>
outputItr set_difference(inputItr1 first1, inputItr1 last1, inputItr2 first2,inputItr2 last2,outputItr destFirst);
template <class inputItr1, class inputItr2,class outputItr,class binaryPredicate>
outputItr set_difference(inputItr1 first1, inputItr1 last1, inputItr2 first2,inputItr2 last2,outputItr destFirst,binaryPredicate op);
template <class inputItr1, class inputItr2,class outputItr>
outputItr set_symmetric_difference(inputItr1 first1, inputItr1 last1, inputItr2 first2,inputItr2 last2,outputItr destFirst);
template <class inputItr1, class inputItr2,class outputItr,class binaryPredicate>
outputItr set_symmetric_difference(inputItr1 first1, inputItr1 last1, inputItr2 first2,inputItr2 last2,outputItr destFirst,binaryPredicate op);

示例代码：

#include <iostream>
#include <list>
#include <string>
#include <numeric>
#include <iterator>
#include <vector>
#include <functional>
#include <algorithm>
using namespace std;
int main() {
int setA[5] = {2,4,5,7,8};
int setB[7] = {3,4,5,6,7,8,10};
int setC[5] = {1,5,6,8,15};
int AdifferenceC[5];
int BsymDiffC[10];
int * lastElement;
ostream_iterator<int> screen(cout," ");
cout << "setA:" << endl;
copy(setA,setA+5,screen);
cout << endl;
cout << "setB:" << endl;
copy(setB,setB+7,screen);
cout << endl;
cout << "setC:" << endl;
copy(setC,setC+5,screen);
cout << endl;
// set_difference
lastElement = set_difference(setA,setA+5,setC,setC+5,AdifferenceC);
cout << "AdifferenceC:" << endl;
copy(AdifferenceC,lastElement,screen);
cout << endl;
// set_symmetric_differenc 对称差
lastElement = set_symmetric_difference(setB,setB+7,setC,setC+5,BsymDiffC);
cout << "BsymDiffC:" << endl;
copy(BsymDiffC,lastElement,screen);
cout << endl;
return 0;
}

运行结果：

setA:
2 4 5 7 8
setB:
3 4 5 6 7 8 10
setC:
1 5 6 8 15
AdifferenceC:
2 4 7
BsymDiffC:
1 3 4 7 10 15