C++ Program to Implement Binary Heap

C++Server Side Programming Programming

A Binary Heap is a complete binary tree which is either Min Heap or Max Heap. In a Max Binary Heap, the key at root must be maximum among all keys present in Binary Heap. This property must be recursively true for all nodes in that Binary Tree. Min Binary 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 index);
   void heapifydown(int index);
   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() {
   return heap.size();
}
void BHeap::Insert(int ele) {
   heap.push_back(ele);
   heapifyup(heap.size() -1);
}
void BHeap::DeleteMin() {
   if (heap.size() == 0) {
      cout<<"Heap is Empty"<<endl;
      return;
   }
   heap[0] = heap.at(heap.size() - 1);
   heap.pop_back();
   heapifydown(0);
   cout<<"Element Deleted"<<endl;
}
int BHeap::ExtractMin() {
   if (heap.size() == 0) {
      return -1;
   }
   else
   return heap.front();
}
void BHeap::showHeap() {
   vector <int>::iterator pos = heap.begin();
   cout<<"Heap --> ";
   while (pos != heap.end()) {
      cout<<*pos<<" ";
      pos++;
   }
   cout<<endl;
}
int BHeap::l(int parent) {
   int l = 2 * parent + 1;
   if (l < heap.size())
      return l;
   else
      return -1;
}
int BHeap::r(int parent) {
   int r = 2 * parent + 2;
   if (r < heap.size())
      return r;
   else
      return -1;
}
int BHeap::par(int child) {
   int p = (child - 1)/2;
   if (child == 0)
      return -1;
   else
      return p;
}
void BHeap::heapifyup(int in) {
   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) {
   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

George John

Updated on: 30-Jul-2019

4K+ Views

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