public void SetNewHead(MiniMaxNode newHead) throws Exception {
MiniMaxNode node = Find(newHead);
if (node == null) {
throw new Exception("No such node: " + newHead.toString());
} else {
this.head = node;
this.head.parent = null;
// Rather than figuring out which empty parents are no long valid,
// Just clear the list and start over. The cost is minimal.
emptyParents.clear();
emptyParents.addAll(FindEmptyParents());
}
}
