/**
* extract minimum from the heap.
*
* <p>minor differences from Cormen et al. pseudocode are present.
*
* @return
*/
public HeapNode extractMin() {
int sentinel = DoubleLinkedCircularList.sentinelKey;
HeapNode z = minimumNode;
if (z != null) {
// detach each child and add it to heap
HeapNode x = z.getChildren().getSentinel().getRight();
// for each child x of z
while (x.getKey() != sentinel) {
HeapNode next = x.getRight();
rootList.insert(x);
x = next;
}
rootList.remove(z);
if (z.getRight().getKey() == z.getKey()) {
minimumNode = null;
} else {
minimumNode = z.getRight();
consolidate();
}
n--;
}
return z;
}
/**
* a depth first search of all nodes (that is, it descends all children of a node before
* proceeding to the next in the current doubly linked circular list).
*
* @param key
* @return
*/
HeapNode search(long key) {
HeapNode node = rootList.getSentinel().getRight();
int sentinel = DoubleLinkedCircularList.sentinelKey;
Stack<HeapNode> stack = new Stack<HeapNode>();
while (!stack.isEmpty() || (node.getKey() != sentinel)) {
if (node.getKey() != sentinel) {
stack.push(node);
node = node.getRight();
} else {
node = stack.pop();
// System.out.println(node.key);
if (node.getKey() == key) {
return node;
}
node = node.getChildren().getSentinel().getRight();
}
}
return null;
}