C++ Programming Code Examples C++ > Data Structures Code Examples C++ Program to Implement Heap C++ Program to Implement Heap This C++ Program demonstrates the implementation of Heap. #include <iostream> #include <cstdlib> #include <vector> #include <iterator> using namespace std; /* Class Declaration */ class Heap { private: vector <int> heap; int left(int parent); int right(int parent); int parent(int child); void heapifyup(int index); void heapifydown(int index); public: Heap() {} void Insert(int element); void DeleteMin(); int ExtractMin(); void DisplayHeap(); int Size(); }; /* Return Heap Size */ int Heap::Size() { return heap.size(); } /* Insert Element into a Heap */ void Heap::Insert(int element) { heap.push_back(element); heapifyup(heap.size() -1); } /* Delete Minimum Element */ void Heap::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; } /* Extract Minimum Element */ int Heap::ExtractMin() { if (heap.size() == 0) { return -1; } else return heap.front(); } /* Display Heap */ void Heap::DisplayHeap() { vector <int>::iterator pos = heap.begin(); cout<<"Heap --> "; while (pos != heap.end()) { cout<<*pos<<" "; pos++; } cout<<endl; } /* Return Left Child */ int Heap::left(int parent) { int l = 2 * parent + 1; if(l < heap.size()) return l; else return -1; } /* Return Right Child */ int Heap::right(int parent) { int r = 2 * parent + 2; if(r < heap.size()) return r; else return -1; } /* Return Parent */ int Heap::parent(int child) { int p = (child - 1)/2; if(child == 0) return -1; else return p; } /* Heapify- Maintain Heap Structure bottom up */ void Heap::heapifyup(int in) { if (in >= 0 && parent(in) >= 0 && heap[parent(in)] > heap[in]) { int temp = heap[in]; heap[in] = heap[parent(in)]; heap[parent(in)] = temp; heapifyup(parent(in)); } } /* Heapify- Maintain Heap Structure top down */ void Heap::heapifydown(int in) { int child = left(in); int child1 = right(in); if (child >= 0 && child1 >= 0 && heap[child] > heap[child1]) { child = child1; } if (child > 0) { int temp = heap[in]; heap[in] = heap[child]; heap[child] = temp; heapifydown(child); } } /* Main Contains Menu */ int main() { Heap h; while (1) { cout<<"------------------"<<endl; cout<<"Operations on Heap"<<endl; cout<<"------------------"<<endl; cout<<"1.Insert Element"<<endl; cout<<"2.Delete Minimum Element"<<endl; cout<<"3.Extract Minimum Element"<<endl; cout<<"4.Print Heap"<<endl; cout<<"5.Exit"<<endl; int choice, element; cout<<"Enter your choice: "; cin>>choice; switch(choice) { case 1: cout<<"Enter the element to be inserted: "; cin>>element; h.Insert(element); break; case 2: h.DeleteMin(); break; case 3: cout<<"Minimum Element: "; 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.DisplayHeap(); break; case 5: exit(1); default: cout<<"Enter Correct Choice"<<endl; } } return 0; }