/**
* Heapify up the treap at the current node to the root.
*
* @param current to heapify.
*/
private void heapify(TreapNode<T> current) {
// Bubble up the heap, if needed
TreapNode<T> parent = (TreapNode<T>) current.parent;
while (parent != null && current.priority > parent.priority) {
Node<T> grandParent = parent.parent;
if (grandParent != null) {
if (grandParent.greater != null && grandParent.greater.equals(parent)) {
// My parent is my grandparents greater branch
grandParent.greater = current;
current.parent = grandParent;
} else if (grandParent.lesser != null && grandParent.lesser.equals(parent)) {
// My parent is my grandparents lesser branch
grandParent.lesser = current;
current.parent = grandParent;
} else {
System.err.println(
"YIKES! Grandparent should have at least one non-NULL child which should be my parent.");
}
current.parent = grandParent;
} else {
root = current;
root.parent = null;
}
if (parent.lesser != null && parent.lesser.equals(current)) {
// LEFT
parent.lesser = null;
if (current.greater == null) {
current.greater = parent;
parent.parent = current;
} else {
Node<T> lost = current.greater;
current.greater = parent;
parent.parent = current;
parent.lesser = lost;
lost.parent = parent;
}
} else if (parent.greater != null && parent.greater.equals(current)) {
// RIGHT
parent.greater = null;
if (current.lesser == null) {
current.lesser = parent;
parent.parent = current;
} else {
Node<T> lost = current.lesser;
current.lesser = parent;
parent.parent = current;
parent.greater = lost;
lost.parent = parent;
}
} else {
// We really shouldn't get here
System.err.println(
"YIKES! Parent should have at least one non-NULL child which should be me.");
}
parent = (TreapNode<T>) current.parent;
}
}
/**
* Splay the tree at the node.
*
* @param node to splay at.
*/
private void splay(Node<T> node) {
Node<T> parent = node.parent;
Node<T> grandParent = (parent != null) ? parent.parent : null;
if (parent == root) {
// Zig step
root = node;
node.parent = null;
if (parent != null) {
if (node == parent.lesser) {
parent.lesser = node.greater;
if (node.greater != null) node.greater.parent = parent;
node.greater = parent;
parent.parent = node;
} else {
parent.greater = node.lesser;
if (node.lesser != null) node.lesser.parent = parent;
node.lesser = parent;
parent.parent = node;
}
}
} else if (parent != null && grandParent != null) {
Node<T> greatGrandParent = grandParent.parent;
if (greatGrandParent != null && greatGrandParent.lesser == grandParent) {
greatGrandParent.lesser = node;
node.parent = greatGrandParent;
} else if (greatGrandParent != null && greatGrandParent.greater == grandParent) {
greatGrandParent.greater = node;
node.parent = greatGrandParent;
} else {
// I am now root!
root = node;
node.parent = null;
}
if ((node == parent.lesser && parent == grandParent.lesser)
|| (node == parent.greater && parent == grandParent.greater)) {
// Zig-zig step
if (node == parent.lesser) {
Node<T> nodeGreater = node.greater;
node.greater = parent;
parent.parent = node;
parent.lesser = nodeGreater;
if (nodeGreater != null) nodeGreater.parent = parent;
Node<T> parentGreater = parent.greater;
parent.greater = grandParent;
grandParent.parent = parent;
grandParent.lesser = parentGreater;
if (parentGreater != null) parentGreater.parent = grandParent;
} else {
Node<T> nodeLesser = node.lesser;
node.lesser = parent;
parent.parent = node;
parent.greater = nodeLesser;
if (nodeLesser != null) nodeLesser.parent = parent;
Node<T> parentLesser = parent.lesser;
parent.lesser = grandParent;
grandParent.parent = parent;
grandParent.greater = parentLesser;
if (parentLesser != null) parentLesser.parent = grandParent;
}
} else {
// Zig-zag step
if (node == parent.lesser) {
Node<T> nodeLesser = node.greater;
Node<T> nodeGreater = node.lesser;
node.greater = parent;
parent.parent = node;
node.lesser = grandParent;
grandParent.parent = node;
parent.lesser = nodeLesser;
if (nodeLesser != null) nodeLesser.parent = parent;
grandParent.greater = nodeGreater;
if (nodeGreater != null) nodeGreater.parent = grandParent;
} else {
Node<T> nodeLesser = node.lesser;
Node<T> nodeGreater = node.greater;
node.lesser = parent;
parent.parent = node;
node.greater = grandParent;
grandParent.parent = node;
parent.greater = nodeLesser;
if (nodeLesser != null) nodeLesser.parent = parent;
grandParent.lesser = nodeGreater;
if (nodeGreater != null) nodeGreater.parent = grandParent;
}
}
}
}
