protected Node erase(K key) {
int value = compare(key, this.key);
if (value == 0) return merge(left, right);
if (value < 0) {
left = left.erase(key);
updateSize();
return this;
}
right = right.erase(key);
updateSize();
return this;
}
public K pollFirst() {
K first = first();
if (first == null) throw new NoSuchElementException();
root.erase(first);
return first;
}
public boolean remove(Object o) {
if (!contains(o)) return false;
//noinspection unchecked
root = root.erase((K) o);
return true;
}
public K pollLast() {
K last = last();
if (last == null) throw new NoSuchElementException();
root.erase(last);
return last;
}