/// <summary>
/// 伸展某个结点
/// </summary>
/// <param name="v">要提升到根结点的结点</param>
/// <returns>返回该结点</returns>
private BinNode <T> Splay(BinNode <T> v)
{
if (v == null)
{
return(null);
}
//p->parent
//g->grandfather
BinNode <T> p, g;
while ((p = v.Parent) != null && (g = p.Parent) != null)
{
BinNode <T> gg = g.Parent;
bool isLChild = g.IsLChild;
if (v.IsLChild)
{
//zig-zig
if (p.IsLChild)
{
g.AttachAsLChild(p.RChild);
p.AttachAsLChild(v.RChild);
p.AttachAsRChild(g);
v.AttachAsRChild(p);
}
//zig-zag
else
{
p.AttachAsLChild(v.RChild);
g.AttachAsRChild(v.LChild);
v.AttachAsLChild(g);
v.AttachAsRChild(p);
}
}
//zag-zag
else if (p.IsRChild)
{
g.AttachAsRChild(p.LChild);
p.AttachAsRChild(v.LChild);
p.AttachAsLChild(g);
v.AttachAsLChild(p);
}
//zag-zig
else
{
p.AttachAsRChild(v.LChild);
g.AttachAsLChild(v.RChild);
v.AttachAsRChild(g);
v.AttachAsLChild(p);
}
//如果g是根结点
if (gg == null)
{
v.Parent = null;
}
//如果不是
else
{
if (isLChild)
{
gg.AttachAsLChild(v);
}
else
{
gg.AttachAsRChild(v);
}
}
UpdateHeight(g);
UpdateHeight(p);
UpdateHeight(v);
}
//如果只剩下一个结点
if ((p = v.Parent) != null)//做一次单旋
{
//zig
if (v.IsLChild)
{
p.AttachAsLChild(v.RChild);
v.AttachAsRChild(p);
}
//zag
else
{
p.AttachAsRChild(v.LChild);
v.AttachAsLChild(p);
}
UpdateHeight(p);
UpdateHeight(v);
}
v.Parent = null;
return(v);
}
