void remove() {
UFNode root = this.find();
if (root != this) for (UFNode child : children) child.parent = root;
else if (!children.isEmpty()) {
Iterator<UFNode> it = children.iterator();
root = it.next();
root.parent = null;
while (it.hasNext()) it.next().parent = root;
root.size = this.size;
}
root.size--;
this.parent = null;
this.size = 1;
}
UFNode find() {
UFNode root = this;
while (root.parent != null) root = root.parent;
UFNode ptr = this;
while (ptr != root) {
UFNode old = ptr;
ptr = ptr.parent;
ptr.children.remove(old);
old.parent = root;
root.children.add(old);
}
return root;
}
int merge(UFNode x) {
x = x.find();
UFNode y = this.find();
if (x != y) {
if (x.size < y.size) {
UFNode temp = x;
x = y;
y = temp;
}
x.size += y.size;
y.size = 0;
y.parent = x;
x.children.add(y);
}
return x.size;
}