Given an array of size N. The task is to sort the array elements by completing functions heapify() and buildHeap() which are used to implement Heap Sort.

Example 1:

Input:
N = 5
arr[] = {4,1,3,9,7}
Output:1 3 4 7 9
Explanation:After sorting elements
using heap sort, elements will be
in order as 1,3,4,7,9.

Example 2:

Input:
N = 10
arr[] = {10,9,8,7,6,5,4,3,2,1}
Output:1 2 3 4 5 6 7 8 9 10
Explanation:After sorting elements
using heap sort, elements will be
in order as 1, 2,3,4,5,6,7,8,9,10.

Your Task :
Complete the functions heapify() and buildheap().

Expected Time Complexity: O(N * Log(N)).
Expected Auxiliary Space: O(1).

Constraints:
1 <= N <= 10⁶
1 <= arr[i] <= 10⁶