C++ Program to Implement Heap Sort

A Heap is a complete binary tree which is either Min Heap or Max Heap. In a Max Heap, the key at root must be maximum among all keys present in Heap. This property must be recursively true for all nodes in that Binary Tree. Min Heap is similar to MinHeap.

Function descriptions

void BHeap::Insert(int ele): Perform insertion operation to insert element in heap.

void BHeap::DeleteMin(): Perform deleteion operation to delete minimum value from heap.

int BHeap::ExtractMin(): Perfrom operation to extract minimum value from heap.

void BHeap::showHeap(): To show the elements of heap.

void BHeap::heapifyup(int in): maintain heap structure in bottom up manner.

void BHeap::heapifydown(int in): maintain heap structure in top down manner.

Example

#include <iostream>
#include <cstdlib>
#include <vector>
#include <iterator>
using namespace std;
class BHeap {
   private:
      vector <int> heap;
      int l(int parent);
      int r(int parent);
      int par(int child);
      void heapifyup(int in);
      void heapifydown(int in);
   public:
      BHeap()
      {}
      void Insert(int element);
      void DeleteMin();
      int ExtractMin();
      void showHeap();
      int Size();
};  
int main() {
   BHeap h;
   while (1) {
      cout<<"1.Insert Element"<<endl;
      cout<<"2.Delete Minimum Element"<<endl;
      cout<<"3.Extract Minimum Element"<<endl;
      cout<<"4.Show Heap"<<endl;
      cout<<"5.Exit"<<endl;
      int c, e;
      cout<<"Enter your choice: ";
      cin>>c;
      switch(c) {
         case 1:
            cout<<"Enter the element to be inserted: ";
            cin>>e;
            h.Insert(e);
            break;
         case 2:
            h.DeleteMin();
            break;
         case 3:
            if (h.ExtractMin() == -1) {
               cout<<"Heap is Empty"<<endl;
            }
            else
               cout<<"Minimum Element: "<<h.ExtractMin()<<endl;
            break;
         case 4:
            cout<<"Displaying elements of Hwap: ";
            h.showHeap();
            break;
         case 5:
            exit(1);
         default:
            cout<<"Enter Correct Choice"<<endl;
      }  
   }
   return 0;
}
int BHeap::Size() //size of heap {
   return heap.size();
}
void BHeap::Insert(int ele) //insert element in heap {
   heap.push_back(ele);//push element into the heap
   heapifyup(heap.size() -1);//call heapifyup() to maintain heap structure
}
void BHeap::DeleteMin() //delete minimum value from heap {
   if (heap.size() == 0) {
      cout<<"Heap is Empty"<<endl;
      return;
   }
   heap[0] = heap.at(heap.size() - 1);
   heap.pop_back();//pop element
   heapifydown(0);
   cout<<"Element Deleted"<<endl;
}
int BHeap::ExtractMin() //extract minimum value from heap
{
   if (heap.size() == 0) {
      return -1;
   }
   else
      return heap.front();
}
void BHeap::showHeap() //show the elements of heap {
   vector <int>::iterator pos = heap.begin();
   cout<<"Heap --> ";
   while (pos != heap.end()) {
      cout<<*pos<<" ";
      pos++;
   }
   cout<<endl;
}
int BHeap::l(int parent) // return left child of node.
{
   int l = 2 * parent + 1;
   if (l < heap.size())
      return l;
   else
      return -1;
}
int BHeap::r(int parent) // return right child of node.
{
   int r = 2 * parent + 2;
   if (r < heap.size())
      return r;
   else
      return -1;
}
int BHeap::par(int child)// return parent
{
   int p = (child - 1)/2;
   if (child == 0)
      return -1;
   else
      return p;
}
void BHeap::heapifyup(int in)//maintain heap structure in bottom up manner.
{
   if (in >= 0 && par(in) >= 0 && heap[par(in)] > heap[in]) {
      int temp = heap[in];
      heap[in] = heap[par(in)];
      heap[par(in)] = temp;
      heapifyup(par(in));
   }
}
void BHeap::heapifydown(int in)//maintain heap structure in top down manner.
{
   int child = l(in);
   int child1 = r(in);
   if (child >= 0 && child1 >= 0 && heap[child] > heap[child1]) {
      child = child1;
   }
   if (child > 0 && heap[in] > heap[child]) {
      int t = heap[in];
      heap[in] = heap[child];
      heap[child] = t;
      heapifydown(child);
   }
}

Output

1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 1
Enter the element to be inserted: 2
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 1
Enter the element to be inserted: 3
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 1
Enter the element to be inserted: 7
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 1
Enter the element to be inserted: 6
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 4
Displaying elements of Hwap: Heap --> 2 3 7 6
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 3
Minimum Element: 2
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 3
Minimum Element: 2
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 2
Element Deleted
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 4
Displaying elements of Hwap: Heap --> 3 6 7
1.Insert Element
2.Delete Minimum Element
3.Extract Minimum Element
4.Show Heap
5.Exit
Enter your choice: 5