private RedBlackBSTNode <Key, Value> Put(RedBlackBSTNode <Key, Value> h, Key key, Value value)
{
if (h == null) //标准的插入操作，和父节点用红链接相连
{
return(new RedBlackBSTNode <Key, Value>(key, value, 1, RED));
}
int cmp = key.CompareTo(h.Key);
if (cmp < 0)
{
h.Left = Put((RedBlackBSTNode <Key, Value>)h.Left, key, value);
}
else if (cmp > 0)
{
h.Right = Put((RedBlackBSTNode <Key, Value>)h.Right, key, value);
}
else
{
h.Val = value;
}
if (IsRed((RedBlackBSTNode <Key, Value>)h.Right) && !IsRed((RedBlackBSTNode <Key, Value>)h.Left)) //左黑右红，左旋转
{
h = RotateLeft(h);
}
if (IsRed((RedBlackBSTNode <Key, Value>)h.Left) && IsRed((RedBlackBSTNode <Key, Value>)h.Left.Left))//连续两个红，右旋转
{
h = RotateRight(h);
}
if (IsRed((RedBlackBSTNode <Key, Value>)h.Left) && IsRed((RedBlackBSTNode <Key, Value>)h.Right)) //左右都为红，执行颜色变换
{
FlipColours(h);
}
h.N = GetNodeSize(h.Left) + GetNodeSize(h.Right) + 1;
return(h);
}
private RedBlackBSTNode <Key, Value> RotateRight(RedBlackBSTNode <Key, Value> h)
{
RedBlackBSTNode <Key, Value> x = (RedBlackBSTNode <Key, Value>)h.Left;
h.Left = x.Right;
x.Right = h;
x.Color = h.Color;
h.Color = RED;
x.N = h.N;
h.N = 1 + GetNodeSize(h.Left) + GetNodeSize(h.Right);
return(x);
}
private void FlipColours(RedBlackBSTNode <Key, Value> h)
{
h.Color = RED;
((RedBlackBSTNode <Key, Value>)h.Left).Color = BLACK;
((RedBlackBSTNode <Key, Value>)h.Right).Color = BLACK;
}
private bool IsRed(RedBlackBSTNode <Key, Value> x) => x != null && x.Color == RED;