STL算法(Algorithms):合并(Merge)

最新推荐文章于 2023-04-29 12:41:02 发布

最新推荐文章于 2023-04-29 12:41:02 发布 · 379 阅读

本文介绍了几种常用的排序算法和集合操作算法，包括merge、inplace_merge、includes等，并提供了具体的代码示例。

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1、merge：将两个序列合并成一个新的序列，并对新的序列排序
原型：
template <class InputIterator1, class InputIterator2, class OutputIterator>
OutputIterator merge ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,OutputIterator result );
template <class InputIterator1, class InputIterator2,class OutputIterator, class Compare>
OutputIterator merge ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,OutputIterator result, Compare comp );
示例：

//mergealgorithmexample
#include<iostream>
#include<algorithm>
#include<vector>
usingnamespacestd;

intmain(){
intfirst[]={5,10,15,20,25};
intsecond[]={50,40,30,20,10};
vector<int>v(10);
vector<int>::iteratorit;

sort(first,first+5);
sort(second,second+5);
merge(first,first+5,second,second+5,v.begin());

cout<<"Theresultingvectorcontains:";
for(it=v.begin();it!=v.end();++it)
cout<<""<<*it;

cout<<endl;

return0;
}

2、inplace_merge：将两个序列合并成一个新的序列,并对新的序列进行归并排序(这两个序列必须要进过排序)
原型：
template <class BidirectionalIterator>
void inplace_merge ( BidirectionalIterator first, BidirectionalIterator middle,
BidirectionalIterator last );

template <class BidirectionalIterator, class Compare>
void inplace_merge ( BidirectionalIterator first, BidirectionalIterator middle,
BidirectionalIterator last, Compare comp );
示例:

//inplace_mergeexample
#include<iostream>
#include<algorithm>
#include<vector>
usingnamespacestd;

intmain(){
intfirst[]={5,10,15,20,25};
intsecond[]={50,40,30,20,10};
vector<int>v(10);
vector<int>::iteratorit;

sort(first,first+5);
sort(second,second+5);

copy(first,first+5,v.begin());
copy(second,second+5,v.begin()+5);

inplace_merge(v.begin(),v.begin()+5,v.end());

cout<<"Theresultingvectorcontains:";
for(it=v.begin();it!=v.end();++it)
cout<<""<<*it;

cout<<endl;

return0;
}

3、includes：测试是一个序列是否在另一个序列中
原型：
template <class InputIterator1, class InputIterator2>
bool includes ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2 );
template <class InputIterator1, class InputIterator2, class Compare>
bool includes ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2, Compare comp );
示例:

//includesalgorithmexample
#include<iostream>
#include<algorithm>
usingnamespacestd;

boolmyfunction(inti,intj){returni<j;}

intmain(){
intcontainer[]={5,10,15,20,25,30,35,40,45,50};
intcontinent[]={40,30,20,10};

sort(container,container+10);
sort(continent,continent+4);

//usingdefaultcomparison:
if(includes(container,container+10,continent,continent+4))
cout<<"containerincludescontinent!"<<endl;

//usingmyfunctionascomp:
if(includes(container,container+10,continent,continent+4,myfunction))
cout<<"containerincludescontinent!"<<endl;

return0;
}

4、set_union：和merge类似，不过新序列中没有重复的元素
原型：
template <class InputIterator1, class InputIterator2, class OutputIterator>
OutputIterator set_union ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,OutputIterator result );
template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
OutputIterator set_union ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,OutputIterator result, Compare comp );
示例：

//set_unionexample
#include<iostream>
#include<algorithm>
#include<vector>
usingnamespacestd;

intmain(){
intfirst[]={5,10,15,20,25};
intsecond[]={50,40,30,20,10};
vector<int>v(10);//0000000000
vector<int>::iteratorit;

sort(first,first+5);//510152025
sort(second,second+5);//1020304050

it=set_union(first,first+5,second,second+5,v.begin());
//51015202530405000

cout<<"unionhas"<<int(it-v.begin())<<"elements.\n";

return0;
}

5、set_intersection：两个序列的交集
原型：
template <class InputIterator1, class InputIterator2, class OutputIterator>
OutputIterator set_intersection ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,OutputIterator result );
template <class InputIterator1, class InputIterator2,class OutputIterator, class Compare>
OutputIterator set_intersection ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,OutputIterator result, Compare comp );
示例：

//set_intersectionexample
#include<iostream>
#include<algorithm>
#include<vector>
usingnamespacestd;

intmain(){
intfirst[]={5,10,15,20,25};
intsecond[]={50,40,30,20,10};
vector<int>v(10);//0000000000
vector<int>::iteratorit;

sort(first,first+5);//510152025
sort(second,second+5);//1020304050

it=set_intersection(first,first+5,second,second+5,v.begin());
//102000000000

cout<<"intersectionhas"<<int(it-v.begin())<<"elements.\n";

return0;
}

6、set_difference：序列(first1,last1)不在序列(first2,last2)中的元素
原型：
template <class InputIterator1, class InputIterator2, class OutputIterator>
OutputIterator set_intersection ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,outputIterator result );
template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
OutputIterator set_intersection ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,OutputIterator result, Compare comp );
示例：

//set_differenceexample
#include<iostream>
#include<algorithm>
#include<vector>
usingnamespacestd;

intmain(){
intfirst[]={5,10,15,20,25};
intsecond[]={50,40,30,20,10};
vector<int>v(10);//0000000000
vector<int>::iteratorit;

sort(first,first+5);//510152025
sort(second,second+5);//1020304050

it=set_difference(first,first+5,second,second+5,v.begin());
//515250000000

cout<<"differencehas"<<int(it-v.begin())<<"elements.\n";

return0;
}

7、set_symmetric_difference：所有不在序列(first1,last1)和序列(first2,last2)中的元素
原型：
template <class InputIterator1, class InputIterator2, class OutputIterator>
OutputIterator set_symmetric_difference ( InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,OutputIterator result );
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 );
示例：

//set_symmetric_differenceexample
#include<iostream>
#include<algorithm>
#include<vector>
usingnamespacestd;

intmain(){
intfirst[]={5,10,15,20,25};
intsecond[]={50,40,30,20,10};
vector<int>v(10);//0000000000
vector<int>::iteratorit;

sort(first,first+5);//510152025
sort(second,second+5);//1020304050

it=set_symmetric_difference(first,first+5,second,second+5,v.begin());
//515253040500000

cout<<"symmetricdifferencehas"<<int(it-v.begin())<<"elements.\n";

return0;
}