/// <summary>
/// Return a new dict with the root key-value pair removed
/// </summary>
AvlNode <T> RemoveRoot()
{
if (IsEmpty)
{
return(this);
}
if (_left.IsEmpty)
{
return(_right);
}
if (_right.IsEmpty)
{
return(_left);
}
//Neither are empty:
if (_left._count < _right._count)
{
//LTDict has fewer, so promote from GTDict to minimize depth
AvlNode <T> min;
var newGt = _right.RemoveMin(out min);
var newRoot = NewOrMutate(min.Value, _left, newGt);
return(newRoot.FixRootBalance());
}
else
{
AvlNode <T> max;
var newLt = _left.RemoveMax(out max);
var newRoot = NewOrMutate(max.Value, newLt, _right);
return(newRoot.FixRootBalance());
}
}
AvlNode <T> RemoveMax(out AvlNode <T> max)
{
if (IsEmpty)
{
max = Empty;
return(Empty);
}
if (_right.IsEmpty)
{
//We are the max:
max = this;
return(_left);
}
else
{
//Go down:
var newGt = _right.RemoveMax(out max);
var newRoot = NewOrMutate(Value, _left, newGt);
return(newRoot.FixRootBalance());
}
}
