public void methodsOfPQ() {
PriorityQueue<Integer> pq = new PriorityQueue<Integer>(); // Default Constructor:
// Queue<Integer> pq = new PriorityQueue<Integer>();
pq.add(10);
pq.add(30);
pq.add(50);
pq.add(40);
pq.add(20);
System.out.println(pq); // [10, 20, 50, 40, 30]
pq.offer(75); // add element randomly anywhere
System.out.println(pq); // [10, 20, 50, 40, 30, 75]
System.out.println(pq.peek()); // 10 | return head of queue and don't touch pq
System.out.println(pq); // [10, 20, 50, 40, 30, 75]
System.out.println(pq.poll()); // 10 | return head and also removes head from pq
System.out.println(pq); // [20, 50, 40, 30, 75]
System.out.println(pq.element()); // 20 | same as peek but throw exception if pq is empty
System.out.println(pq); // [20, 50, 40, 30, 75]
pq.remove(); // 20 | same as poll but throw exception when queue is empty
System.out.println(pq); // [50, 40, 30, 75]
List<Integer> ls = new ArrayList<Integer>();
ls.add(1000);
ls.add(2000);
pq.addAll(ls);
System.out.println(pq); // [30, 40, 50, 75, 1000, 2000]
pq.removeAll(ls);
System.out.println(pq); // [30, 40, 50, 75]
ls.clear(); // empty ls
ls.add(101);
ls.add(102);
pq.addAll(ls);
pq.retainAll(ls); // all element will be removed except ls
System.out.println(pq); // [101, 102]
System.out.println(pq.containsAll(ls)); // true
System.out.println("********************************************");
// Queue<String> q=new PriorityQueue<String>();
}
/**
* Recursively search for the k nearest neighbors to target.
*
* @param target target point
* @param maxDistance maximum distance
* @param k number of neighbors to find
*/
private PriorityQueue<HeapItem> search(final double[] target, double maxDistance, final int k) {
PriorityQueue<HeapItem> heap = new PriorityQueue<HeapItem>();
if (root == null) {
return heap;
}
double tau = maxDistance;
final FastQueue<Node> nodes = new FastQueue<Node>(20, Node.class, false);
nodes.add(root);
while (nodes.size() > 0) {
final Node node = nodes.getTail();
nodes.removeTail();
final double dist = distance(items[node.index], target);
if (dist <= tau) {
if (heap.size() == k) {
heap.poll();
}
heap.add(new HeapItem(node.index, dist));
if (heap.size() == k) {
tau = heap.element().dist;
}
}
if (node.left != null && dist - tau <= node.threshold) {
nodes.add(node.left);
}
if (node.right != null && dist + tau >= node.threshold) {
nodes.add(node.right);
}
}
return heap;
}
@Override
public T element() {
pruneToDuration();
return queue.element().getWrapped();
}