Deleting in a Heap

Procedure :
Copy the last element to root i.e index 1.
Shift the root element to last element of heap.
Set i as 1 (root) and j as 2*i (left child of root).
Perform the following until j < size - 1.
Find which of the child is greater.
Set j to point on that child.
If the child element (j) is greater than parent element (i), swap them.
Set i as j and j as 2*j after each iteration. 
int deleteFromHeap(int h[], int size) {
​
	// Copy last element to root and first element to last place
	int lastElement = h[size];
	int firstElement = h[1];
	h[1] = lastElement;
	h[size] = firstElement;
​
	// Keep i at root and j at left child of root initially
	int i = 1, j = 2*i;
​
	while(j < size-1) {
​
		// Find out if left child is greater or right child
		if (h[j+1] > h[j]) 
			j = j + 1;
	
		// If child is greater than parent, interchange
		if (h[j] > h[i]) {
			int temp = h[i];
			h[i] = h[j];
			h[j] = temp;
			// Set i to j and j to left child of j
			i = j;
			j = 2*j;
		} else {
			break;
		}
	}
	return firstElement;
​
}
By calling the same function n times, heap sort can be implemented.
Last modified 3yr ago