C++ Code Snippet (2) _ algorithm

unique：

Removes duplicate elements that are adjacent to each other in a specified range.
unique函数

#include<vector>

#include<algorithm>

#include<functional>

#include<iostream>

#include<ostream>



usingnamespacestd;



//Return whether modulus of elem1 is equal to modulus of elem2

boolmod_equal (intelem1,intelem2 )

{

if( elem1<0)

elem1=-elem1;

if( elem2<0)

elem2=-elem2;

returnelem1==elem2;

};



intmain( )

{

vector<int>v1;

vector<int>::iterator v1_Iter1, v1_Iter2, v1_Iter3,

v1_NewEnd1, v1_NewEnd2, v1_NewEnd3;



inti;

for( i=0; i<=3; i++)

{

v1.push_back(5);

v1.push_back(-5);

}



intii;

for( ii=0; ii<=3; ii++)

{

v1.push_back(4);

}

v1.push_back(7);



cout<<"Vector v1 is (";

for( v1_Iter1=v1.begin( ) ; v1_Iter1!=v1.end( ) ; v1_Iter1++)

cout<<v1_Iter1<<"";

cout<<")."<<endl;



//Remove consecutive duplicates

v1_NewEnd1=unique ( v1.begin ( ) , v1.end ( ) );



cout<<"Removing adjacent duplicates from vector v1 givesn (";

for( v1_Iter1=v1.begin( ) ; v1_Iter1!=v1_NewEnd1 ; v1_Iter1++)

cout<<v1_Iter1<<"";

cout<<")."<<endl;



//Remove consecutive duplicates under the binary prediate mod_equals

v1_NewEnd2=unique ( v1.begin ( ) , v1_NewEnd1 , mod_equal );



cout<<"Removing adjacent duplicates from vector v1 under then"

<<"binary predicate mod_equal givesn (";

for( v1_Iter2=v1.begin( ) ; v1_Iter2!=v1_NewEnd2 ; v1_Iter2++)

cout<<v1_Iter2<<"";

cout<<")."<<endl;



//Remove elements if preceded by an element that was greater

v1_NewEnd3=unique ( v1.begin ( ) , v1_NewEnd2, greater<int>( ) );



cout<<"Removing adjacent elements satisfying the binaryn"

<<"predicate mod_equal from vector v1 gives (";

for( v1_Iter3=v1.begin( ) ; v1_Iter3!=v1_NewEnd3 ; v1_Iter3++)

cout<<v1_Iter3<<"";

cout<<")."<<endl;

}


sort：

Arranges the elements in a specified range into a nondescending order or according to an ordering criterion specified by a binary predicate.
代码#include<vector>

#include<algorithm>

#include<functional>//For greater( )

#include<iostream>



//Return whether first element is greater than the second

boolUDgreater (intelem1,intelem2 )

{

returnelem1>elem2;

}



intmain( )

{

usingnamespacestd;

vector<int>v1;

vector<int>::iterator Iter1;



inti;

for( i=0; i<=5; i++)

{

v1.push_back(2i );

}



intii;

for( ii=0; ii<=5; ii++)

{

v1.push_back(2ii+1);

}



cout<<"Original vector v1 = (";

for( Iter1=v1.begin( ) ; Iter1!=v1.end( ) ; Iter1++)

cout<<Iter1<<"";

cout<<")"<<endl;



sort( v1.begin( ), v1.end( ) );

cout<<"Sorted vector v1 = (";

for( Iter1=v1.begin( ) ; Iter1!=v1.end( ) ; Iter1++)

cout<<Iter1<<"";

cout<<")"<<endl;



//To sort in descending order. specify binary predicate

sort( v1.begin( ), v1.end( ), greater<int>( ) );

cout<<"Resorted (greater) vector v1 = (";

for( Iter1=v1.begin( ) ; Iter1!=v1.end( ) ; Iter1++)

cout<<Iter1<<"";

cout<<")"<<endl;



//A user-defined (UD) binary predicate can also be used

sort( v1.begin( ), v1.end( ), UDgreater );

cout<<"Resorted (UDgreater) vector v1 = (";

for( Iter1=v1.begin( ) ; Iter1!=v1.end( ) ; Iter1++)

cout<<Iter1<<"";

cout<<")"<<endl;

}


binary_search

Tests whether there is an element in a sorted range that is equal to a specified value or that is equivalent to it in a sense specified by a binary predicate.

代码#include<list>

#include<vector>

#include<algorithm>

#include<iostream>



//Return whether modulus of elem1 is less than modulus of elem2

boolmod_lesser (intelem1,intelem2 )

{

if(elem1<0)

elem1=-elem1;

if(elem2<0)

elem2=-elem2;

returnelem1<elem2;

}



intmain( )

{

usingnamespacestd;



list<int>L;

list<int>::iterator Iter;

boolb1, b2;



L.push_back(50);

L.push_back(10);

L.push_back(30);

L.push_back(20);

L.push_back(25);

L.push_back(5);



L.sort( );



cout<<"L = (";

for( Iter=L.begin( ) ; Iter!=L.end( ) ; Iter++)

cout<<Iter<<"";

cout<<")"<<endl;



b1=binary_search( L.begin( ), L.end( ),10);

if( b1 )

cout<<"There is an element in list L with a value equal to 10."

<<endl;

else

cout<<"There is no element in list L with a value equal to 10."

<<endl;

//a binary_search under the binary predicate greater

L.sort ( greater<int>( ) );

b2=binary_search( L.begin( ), L.end( ),10, greater<int>( ) );

if( b2 )

cout<<"There is an element in list L with a value equivalent to 10"

<<"under greater than."<<endl;

else

cout<<"No element in list L with a value equivalent to 10"

<<"under greater than."<<endl;



//a binary_search under the user-defined binary predicate mod_lesser

vector<int>v1;

vector<int>::iterator Iter1;

inti;

for( i=-2; i<=4; i++)

{

v1.push_back( i );

}

sort ( v1.begin ( ) , v1.end ( ) , mod_lesser );



cout<<"Ordered under mod_lesser, vector v1 = (";

for( Iter1=v1.begin( ) ; Iter1!=v1.end( ) ; Iter1++)

cout<<Iter1<<"";

cout<<")"<<endl;



boolb3=binary_search( v1.begin( ), v1.end( ),-3, mod_lesser );

if( b3 )

cout<<"There is an element with a value equivalent to -3"

<<"under mod_lesser."<<endl;

else

cout<<"There is not an element with a value equivalent to -3"

<<"under mod_lesser."<<endl;

}

原文链接: https://www.cnblogs.com/answeryi/archive/2010/10/10/1847249.html

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