STL Common Algorithm (algorithms) Introduction (STL sorting algorithm, non-variable sequence queue) _c language

Algorithm: Used to process elements within a cluster. They can search, sort, modify, and use those elements for different purposes. An action or function that is applied to a container to handle its memory in various ways, such as sort (sort), copy (copy) ...

The algorithm is embodied by the template function, which is not a member function of the container class, is a stand-alone function, they can be used in STL container, and can be used in ordinary C + + arrays.

Header files: #include <algorithm>

There are 4 kinds of basic algorithms in the STL generic algorithm:

1 variable-order queue algorithm: Can change the data in the container;
2 non-variable sequence queue algorithm: processing the data in the container without changing them;
3 Sorting value algorithm: Inclusion of the value in the container sorting and merging algorithm, there are two fork search algorithm,
4 General numerical algorithm: This kind of algorithm is not many, involves the useful arithmetic operation in the specialized domain, the independent inclusion in the header file <numeric>.

STL algorithm is not only for STL containers, but also for the general container is applicable.

Copy Code code as follows:

A sequence-changing queue algorithm

#include <iostream>
#include <algorithm>
#include <iterator>

The output iterator is used below Ostream_iterator

using namespace Std;

int main (void)
{int arr0[6]= {1,12,3,2,1215,90};
int arr1[7];
int arr2[6]= {2,5,6,9,0,-56};

Copy an array aar to arr1
Copy (Arr0, (arr0+6), arr1);

cout<< "arr0[6] Copy to Arr1[7],now arr1:" <<endl;
for (int i=0; i<7; i++)
cout<< "" <<arr1[i];

The last array element is not assigned a value, so the output is a random number

Flip the sorted arr

Reverse (arr0,arr0+6);
cout<< "\ n" << "arr reversed, now arr:" <<endl;

Copy to output iterator
Copy (arr0,arr0+6,ostream_iterator<int> (cout, ""));

Exchange Arr0 and ARR2 sequences

Swap_ranges (ARR0,ARR0+6,ARR2);

cout<< "\ r" << "Arr0 swaped to ARR2, and now arr0 ' content:" <<endl;
Copy (arr0,arr0+6,ostream_iterator<int> (cout, ""));

cout<< "\ n" << "ARR2:" <<endl;
Copy (arr2,arr2+6,ostream_iterator<int> (cout, ""));

return 0;
}

Non-variable sequential queue algorithm (member statistic calculation, search matching)

Copy Code code as follows:

The algorithm of non-variable sequence queue

#include <iostream>
#include <vector>
#include <algorithm>

using namespace Std;

int main (void)
{int a[10]= {12,31,5,2,23,121,0,89,34,66};

Vector<int> v1 (a,a+10);
Vector<int>::iterator result1,result2; RESULT1 and RESULT2 are random access iterators

Result1=find (V1.begin (), V1.end (), 2); Find the 2,RESULT1 in V1 to point to 2 in V1

Result2=find (V1.begin (), V1.end (), 8); Not found in the V1 8,result2 is pointing to V1.end ()

Cout<<result1-v1.begin () <<endl; 3-0=3 or 4-1=3, the screen result is 3.
Cout<<result2-v1.end () <<endl; 10-10=0;

int b[9]= {5,2,23,54,5,5,5,2,2};

cout<< "a[10]={12,31,5,2,23,121,0,89,34,66};\n";
cout<< "b[9]={5,2,23,54,5,5,5,2,2};\n";

Vector<int> v2 (a+2,a+8);
Vector<int> v3 (b,b+4);

Result1=search (V1.begin (), V1.end (), V2.begin (), V2.end ());

cout<<*result1<<endl;
The sequence V2,RESULT1 pointed to the location where V2 started in the V1 in the V1

Result1=search (V1.begin (), V1.end (), V3.begin (), V3.end ());

cout<<* (result1-1) <<endl;
The sequence V3,result pointed to V1.end () was not found in the V1, and the screen prints out the last element of the V1 66

Vector<int> v4 (B,B+9);

int I=count (V4.begin (), V4.end (), 5);
int J=count (V4.begin (), V4.end (), 2);

cout<< "There are" <<i<< "members of V4 Equel to 5" <<endl;
cout<< "There are" <<j<< "members of V4 Equel to 2" <<endl;

Calculate how many members in the V4 are equal to 5, 2
return 0;
}

Sorting algorithm

Copy Code code as follows:

Sorting value algorithm

#include <iostream>
#include <algorithm>
using namespace Std;

int main (void)
{int a[10]= {12,0,5,3,6,8,9,34,32,18};
int b[5]= {5,3,6,8,9};
int d[15];

Sort (a,a+10);
cout<< "Sorted a[10]:";
for (int i=0; i<10; i++)
cout<<a[i]<< "";

Sort (b,b+5); 3 5 6 8 8

if (includes (a,a+10,b,b+5))//Whether an array contains another array
cout<< "\ n" << "sorted B are included in a." <<endl;
Else
cout<< "sorted a dosn ' t contain sorted b!";

Merge (A,a+10,b,b+5,d); Merge

cout<< "a[10]={12,0,5,3,6,8,9,34,32,18};\n";
cout<< "b[5]={5,3,6,8,9};\n";
cout<< "merge (a,a+10,b,b+5,d); \ n";
cout<< "then d[15]:\n";
for (int j=0; j<15; j + +)
cout<<d[j]<< "";
return 0;
}