STL 之includes,set_intersection,set_union,set_difference,set_symmetric_difference

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
 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
 #include

 #include
 #include
 #include
 #include
 #include

 #include

 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
 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
 #include

 #include
 #include
 #include
 #include
 #include

 #include

 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
 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
 #include

 #include
 #include
 #include
 #include
 #include

 #include

 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