heap in c code example

Example 1: heapify in c

// Max-Heap data structure in C

#include <stdio.h>
int size = 0;
void swap(int *a, int *b)
{
  int temp = *b;
  *b = *a;
  *a = temp;
}
void heapify(int array[], int size, int i)
{
  if (size == 1)
  {
    printf("Single element in the heap");
  }
  else
  {
    int largest = i;
    int l = 2 * i + 1;
    int r = 2 * i + 2;
    if (l < size && array[l] > array[largest])
      largest = l;
    if (r < size && array[r] > array[largest])
      largest = r;
    if (largest != i)
    {
      swap(&array[i], &array[largest]);
      heapify(array, size, largest);
    }
  }
}
void insert(int array[], int newNum)
{
  if (size == 0)
  {
    array[0] = newNum;
    size += 1;
  }
  else
  {
    array[size] = newNum;
    size += 1;
    for (int i = size / 2 - 1; i >= 0; i--)
    {
      heapify(array, size, i);
    }
  }
}
void deleteRoot(int array[], int num)
{
  int i;
  for (i = 0; i < size; i++)
  {
    if (num == array[i])
      break;
  }

  swap(&array[i], &array[size - 1]);
  size -= 1;
  for (int i = size / 2 - 1; i >= 0; i--)
  {
    heapify(array, size, i);
  }
}
void printArray(int array[], int size)
{
  for (int i = 0; i < size; ++i)
    printf("%d ", array[i]);
  printf("\n");
}
int main()
{
  int array[10];

  insert(array, 3);
  insert(array, 4);
  insert(array, 9);
  insert(array, 5);
  insert(array, 2);

  printf("Max-Heap array: ");
  printArray(array, size);

  deleteRoot(array, 4);

  printf("After deleting an element: ");

  printArray(array, size);
}

Example 2: heap in java

In Java PriorityQueue can be used as a Heap.

Min Heap
PriorityQueue<Integer> minHeap = new PriorityQueue<>();


Max Heap:
PriorityQueue<Integer> maxHeap = new PriorityQueue<>(Comparator.reverseOrder());

Example 3: heap

A heap is a tree-based data structure in which all the nodes of the tree are in a specific order. For example, if is the parent node of , then the value of follows a specific order with respect to the value of and the same order will be followed across the tree.

Example 4: max heap c++

#include <iostream>
using namespace std;
void max_heap(int *a, int m, int n) {
   int j, t;
   t = a[m];
   j = 2 * m;
   while (j <= n) {
      if (j < n && a[j+1] > a[j])
         j = j + 1;
      if (t > a[j])
         break;
      else if (t <= a[j]) {
         a[j / 2] = a[j];
         j = 2 * j;
      }
   }
   a[j/2] = t;
   return;
}
void build_maxheap(int *a,int n) {
   int k;
   for(k = n/2; k >= 1; k--) {
      max_heap(a,k,n);
   }
}
int main() {
   int n, i;
   cout<<"enter no of elements of array\n";
   cin>>n;
   int a[30];
   for (i = 1; i <= n; i++) {
      cout<<"enter elements"<<" "<<(i)<<endl;
      cin>>a[i];
   }
   build_maxheap(a,n);
   cout<<"Max Heap\n";
   for (i = 1; i <= n; i++) {
      cout<<a[i]<<endl;
   }
}