Algorithm for deletion from a max_heap
note: deletion always deletes the root!

1)Remove the value from the root

2)Put the value in the last leaf in its place in the root

3)Physically delete the last leaf

4) Do the “trickle down”: p=root; while p is not a leaf and p<either child, swap with larger child

Slide 3

"Element delete_max_heap(int * n)"

Element delete_max_heap(int * n) {
/* delete element with the highest key from the heap */
int parent, child;
element item, temp;
if(HEAP_EMPTY(*n)) {
fprintf(stderr, “The heap is empty \n”);
exit(1);
}
…… continued on next slide

"/* save value of the..."

/* save value of the element with the highest key */
item = heap[0];
/* use last element in heap to adjust heap */
temp = heap[(*n)--];
parent = 0;
child = 1;
while (child < *n) {
/* find the larger child of the current parent */
if (child < *n) && (heap[child].key < heap[child+1].key)
child++;
if(temp.key >= heap[child].key) break;
/* move to the next lower level */
heap[parent] = heap[child];
parent = child
child = 2*child + 1;
}
heap[parent] = temp;
return item

}


	1)Remove the value from the root
	2)Put the value in the last leaf in its place in the root
	3)Physically delete the last leaf
	4) Do the “trickle down”: p=root; while p is not a leaf and p<either child, swap with larger child


	Element delete_max_heap(int * n) { /* delete element with the highest key from the heap / int parent, child; element item, temp; if(HEAP_EMPTY(n)) { fprintf(stderr, “The heap is empty \n”); exit(1); } …… continued on next slide


	/* save value of the element with the highest key / item = heap[0]; / use last element in heap to adjust heap / temp = heap[(n)--]; parent = 0; child = 1; while (child < n) { / find the larger child of the current parent / if (child < n) && (heap[child].key < heap[child+1].key) child++; if(temp.key >= heap[child].key) break; /* move to the next lower level / heap[parent] = heap[child]; parent = child child = 2child + 1; } heap[parent] = temp; return item
	}