fig21_37.cpp

《c＋＋大学教程》源码

// Fig. 21.37: fig21_37.cpp
// Standard library algorithms push_heap, pop_heap, 
// make_heap and sort_heap.
#include <iostream>

using std::cout;
using std::endl;

#include <algorithm>
#include <vector>

int main()
{
   const int SIZE = 10;
   int a[ SIZE ] = { 3, 100, 52, 77, 22, 31, 1, 98, 13, 40 };
   std::vector< int > v( a, a + SIZE ), v2;
   std::ostream_iterator< int > output( cout, " " );

   cout << "Vector v before make_heap:\n";
   std::copy( v.begin(), v.end(), output );

   // create heap from vector v
   std::make_heap( v.begin(), v.end() );
   
   cout << "\nVector v after make_heap:\n";
   std::copy( v.begin(), v.end(), output );
   
   // sort elements of v with sort_heap
   std::sort_heap( v.begin(), v.end() );
   
   cout << "\nVector v after sort_heap:\n";
   std::copy( v.begin(), v.end(), output );

   // perform the heapsort with push_heap and pop_heap
   cout << "\n\nArray a contains: ";
   std::copy( a, a + SIZE, output );

   cout << endl;

   // place elements of array a into v2 and 
   // maintain elements of v2 in heap
   for ( int i = 0; i < SIZE; ++i ) {
      v2.push_back( a[ i ] );
      std::push_heap( v2.begin(), v2.end() );      
      cout << "\nv2 after push_heap(a[" << i << "]): ";
      std::copy( v2.begin(), v2.end(), output );

   } // end for
   
   cout << endl;

   // remove elements from heap in sorted order
   for ( int j = 0; j < v2.size(); ++j ) {
      cout << "\nv2 after " << v2[ 0 ] << " popped from heap\n";
      std::pop_heap( v2.begin(), v2.end() - j );
      std::copy( v2.begin(), v2.end(), output );

   } // end for

   cout << endl;

   return 0;

} // end main

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