C++/STL Algorithms Heap/make heap

Sort vector1 using make_heap and sort_heap

<source lang="cpp">

1. include <iostream>
2. include <cassert>
3. include <algorithm>
4. 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

*/        
 </source>

Use make_heap to convert collection into a heap

<source lang="cpp">

/* 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.
*/

1. include <iostream>
2. include <vector>
3. include <deque>
4. include <list>
5. include <set>
6. include <map>
7. include <string>
8. include <algorithm>
9. include <iterator>
10. include <functional>
11. 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

*/      
 </source>

Use std::make_heap to create heap from a vector

<source lang="cpp">

1. include <iostream>

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

1. include <algorithm>
2. include <vector>
3. 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

*/       
 </source>