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Create Heap Data Structure
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AyushiChakrabarty authored Nov 4, 2020
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111 changes: 111 additions & 0 deletions Heap Data Structure
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//HEAPS
#include<iostream>
using namespace std;


//function to check whether given set of arrays is a max heap or not
int check_heap(int c[],int count, int n)
{
if( count>(n-2)/2)
return 1;

if(c[count]>=c[2*count + 2] && c[count]>=c[2*count +1] && check_heap(c, 2*count + 2, n) && check_heap(c, 2* count +1,n))
return 1;

return 0;
}


void heapify(int arr[], int n, int i)
{
int largest = i;
int l = 2*i + 1;
int r = 2*i + 2;

// If left child is larger than root
if (l < n && arr[l] > arr[largest])
largest = l;

// If right child is larger than largest so far
if (r < n && arr[r] > arr[largest])
largest = r;

// If largest is not root
if (largest != i)
{
swap(arr[i], arr[largest]);

// Recursively heapify the affected sub-tree
heapify(arr, n, largest);
}
}


void heapSort(int arr[], int n)
{
// Build heap (rearrange array)
for (int i = n / 2 - 1; i >= 0; i--)
heapify(arr, n, i);

// One by one extract an element from heap
for (int i=n-1; i>0; i--)
{
// Move current root to end
swap(arr[0], arr[i]);

// call max heapify on the reduced heap
heapify(arr, i, 0);
}
}

/* A utility function to print array of size n */
void printArray(int arr[], int n)
{
for (int i=0; i<n; ++i)
cout << arr[i] << " ";
cout << "\n";
}

int main()
{
int i;
int l1, l2;
int a[]={16,4,10,14,7,9,3,2,8,1};
int b[]={16,10,14,7,8,9,3,2,4,1};

l1=sizeof(a)/sizeof(int);
l2=sizeof(b)/sizeof(int);

int result1=check_heap(a,0,l1);
int result2=check_heap(b,0,l2);

//check the first array
if(result1==1)
cout<<"First case: Is a HEAP\n";
else
cout<<"First case: Is not a HEAP\n";

//check the second array
if(result2==1)
cout<<"Second case: Is a HEAP\n";
else
cout<<"Second case: Is not a HEAP\n";

cout<<"\n";
// Heapify
cout<<"First case: Before heapification:\n";
printArray(a, l1);
heapSort(a, l1);

cout << "Sorted array-1 is \n";
printArray(a, l1);
cout<<"Heapified................."<<"\n";

heapSort(b, l2);

cout<<"Second case: Sorted array-2 is \n";
printArray(b, l2);



}

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