chapter11-28.cpp

C++STL程序员开发指南

//文件名:CHAPTER11-28.cpp
#include <vector>
#include <algorithm>
#include <functional>      // For greater<int>( )
#include <iostream>
// Return whether first element is greater than the second
bool UDgreater ( int elem1, int elem2 )
{   return elem1 > elem2;}
int main( )
{
   using namespace std;
   vector <int> v1;
   vector <int>::iterator Iter1;
   for (int i = 0 ; i <= 5 ; i++ ) {v1.push_back( 3 * i );   }
   for (int ii = 0 ; ii <= 5 ; ii++ ) {v1.push_back( 3 * ii + 1 );   }
   for (int iii = 0 ; iii <= 5 ; iii++ ) {v1.push_back( 3 * iii +2 );   }
   cout << "Original vector:\n v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ ) cout << *Iter1 << " ";
   cout << ")" << endl;
   nth_element(v1.begin( ), v1.begin( ) + 3, v1.end( ) );
   cout << "Position 3 partitioned vector:\n v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ ) cout << *Iter1 << " ";
   cout << ")" << endl;
   // To sort in descending order, specify binary predicate
   nth_element( v1.begin( ), v1.begin( ) + 4, v1.end( ),greater<int>( ) );
   cout << "Position 4 partitioned (greater) vector:\n v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ ) cout << *Iter1 << " ";
   cout << ")" << endl;
   random_shuffle( v1.begin( ), v1.end( ) );
   cout << "Shuffled vector:\n v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ ) cout << *Iter1 << " ";
   cout << ")" << endl;
   // A user-defined (UD) binary predicate can also be used
   nth_element( v1.begin( ), v1.begin( ) + 5, v1.end( ), UDgreater );
   cout << "Position 5 partitioned (UDgreater) vector:\n v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )    cout << *Iter1 << " ";
   cout << ")" << endl;
}