//Starts at the top of the tree and ensures the tree continues to be a min heap fixing when needed
void Heap::fix_down(const int& t) {
int left_index = t * 2;
int right_index = (t * 2) + 1;
// if two children
if (right_index <= position) {
// check for the smallest of the children and treat like one child but recurse
if (tree[left_index]->weight < tree[right_index]->weight) {
if (tree[left_index]->weight < tree[t]->weight) {
swap(left_index, t);
fix_down(left_index);
}
}
else {
if (tree[right_index]->weight < tree[t]->weight) {
swap(right_index, t);
fix_down(right_index);
}
}
}
// one child
else if (left_index <= position) {
if (tree[left_index]->weight < tree[t]->weight)
swap(left_index, t);
}
}
Item pq_delmax()
{
assert(N > 0);
exch(pq[1], pq[N]);
fix_down(pq, 1, N - 1);
return pq[N--];
}
//Takes a node out of the top of the tree
HNode* Heap::dequeue() {
count--;
assert(position);
HNode* ret = tree[1];
swap(1, position--);
fix_down(1);
return ret;
}
NO *remover_heap(HEAP_ESTATICA *heap) {
if (!vazia_heap(heap)) {
NO *no = heap->vetor[0];
heap->vetor[0] = heap->vetor[heap->fim];
heap->fim--;
fix_down(heap);
return no;
}
return NULL;
}
