C++ Tutorial/STL Algorithms Heap/make heap

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Sort vector1 using make_heap and sort_heap

#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
  vector<int> vector1(5);
  for (int i = 0; i < 5; ++i)
    vector1[i] = i;
  // Shuffle the elements again:
  random_shuffle(vector1.begin(), vector1.end());

  make_heap(vector1.begin(), vector1.end());
  sort_heap(vector1.begin(), vector1.end());
  // Verify that the array is sorted:
  for (int i = 0; i < 5; ++i)
     cout << vector1[i];
  return 0;
}
01234

Use make_heap to convert collection into a heap

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */

#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;
    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << " ";
    }
    std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}

using namespace std;
int main()
{
    vector<int> coll;
    INSERT_ELEMENTS(coll,3,7);
    INSERT_ELEMENTS(coll,5,9);
    INSERT_ELEMENTS(coll,1,4);
    PRINT_ELEMENTS (coll, "on entry:           ");
    // convert collection into a heap
    make_heap (coll.begin(), coll.end());
    PRINT_ELEMENTS (coll, "after make_heap():  ");
}
on entry:           3 4 5 6 7 5 6 7 8 9 1 2 3 4
after make_heap():  9 8 6 7 7 5 5 3 6 4 1 2 3 4

Use std::make_heap to create heap from a vector

#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
#include <vector>
#include <iterator>
int main()
{
   int a[ 10 ] = { 3, 10, 52, 77, 22, 31, 1, 98, 13, 40 };
   std::vector< int > v( a, a + 10 ); // copy of a
   std::vector< int > v2;
   std::ostream_iterator< int > output( cout, " " );
   std::copy( v.begin(), v.end(), output );
   std::make_heap( v.begin(), v.end() ); // create heap from vector v
   cout << "\n\n";
   std::copy( v.begin(), v.end(), output );
   cout << endl;
   return 0;
}
3 10 52 77 22 31 1 98 13 40
98 77 52 13 40 31 1 10 3 22