private BaseNode <TKey, TValue> DeleteNode(BaseNode <TKey, TValue> x, TKey key)
{
if (x == null)
{
return(null);
}
int cmp = key.CompareTo(x.key);
if (cmp < 0)
{
x.left = DeleteNode(x.left, key);
}
else if (cmp > 0)
{
x.right = DeleteNode(x.right, key);
}
else
{
if (x.right == null)
{
return(x.left);
}
if (x.left == null)
{
return(x.right);
}
BaseNode <TKey, TValue> t = x;
x = MinimumNode(t.right);
x.right = DeleteMinimum(t.right);
x.left = t.left;
}
x.UpdateSize();
return(x);
}
/// <summary>
/// Randomized insertion.
/// make new node the root with uniform probability
/// </summary>
/// <param name="x"></param>
/// <param name="key"></param>
/// <param name="val"></param>
/// <returns></returns>
internal override BaseNode <TKey, TValue> PutKey(BaseNode <TKey, TValue> x, TKey key, TValue val)
{
if (x == null)
{
return(new BaseNode <TKey, TValue>(key, val, 1));
}
int cmp = key.CompareTo(x.key);
if (cmp == 0)
{
x.val = val;
return(x);
}
if (StdRandom.bernoulli(1.0 / (x.Size + 1.0)))
{
return(PutRoot(x, key, val));
}
if (cmp < 0)
{
x.left = PutKey(x.left, key, val);
}
else
{
x.right = PutKey(x.right, key, val);
}
x.UpdateSize();
return(x);
}
private BaseNode <TKey, TValue> DeleteMinimum(BaseNode <TKey, TValue> x)
{
if (x.left == null)
{
return(x.right);
}
x.left = DeleteMinimum(x.left);
x.UpdateSize();
return(x);
}
private BaseNode <TKey, TValue> RotateLeft(BaseNode <TKey, TValue> h)
{
var x = h.right;
h.right = x.left;
x.left = h;
h.UpdateSize();
x.UpdateSize();
return(x);
}
/// <summary>
/// Insert key-value pair into symbol table (nonrecursive version).
/// </summary>
/// <param name="key">key to insert</param>
/// <param name="val">value for key</param>
public override void Put(TKey key, TValue val)
{
int cmp = 0;
var z = new BaseNode <TKey, TValue>(key, val, 1);
if (root == null)
{
root = z;
return;
}
BaseNode <TKey, TValue> parent = null, x = root;
while (x != null)
{
parent = x;
cmp = key.CompareTo(x.key);
if (cmp < 0)
{
x = x.left;
}
else if (cmp > 0)
{
x = x.right;
}
else
{
x.val = val;
return;
}
}
cmp = key.CompareTo(parent.key);
if (cmp < 0)
{
parent.left = z;
}
else
{
parent.right = z;
}
parent.UpdateSize();
}
internal override BaseNode <TKey, TValue> PutKey(BaseNode <TKey, TValue> x, TKey key, TValue val)
{
if (x == null)
{
return(new BaseNode <TKey, TValue>(key, val, 1));
}
int cmp = key.CompareTo(x.key);
if (cmp < 0)
{
x.left = PutKey(x.left, key, val);
}
else if (cmp > 0)
{
x.right = PutKey(x.right, key, val);
}
else
{
x.val = val;
}
x.UpdateSize();
return(x);
}
private BaseNode <TKey, TValue> Remove(BaseNode <TKey, TValue> x, TKey key)
{
if (x == null)
{
return(null);
}
int cmp = key.CompareTo(x.key);
if (cmp == 0)
{
x = joinLR(x.left, x.right);
}
else if (cmp < 0)
{
x.left = Remove(x.left, key);
}
else
{
x.right = Remove(x.right, key);
}
x.UpdateSize();
return(x);
}
/// <summary>
/// Randomized deletion.
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
private BaseNode <TKey, TValue> joinLR(BaseNode <TKey, TValue> a, BaseNode <TKey, TValue> b)
{
if (a == null)
{
return(b);
}
if (b == null)
{
return(a);
}
if (StdRandom.bernoulli((double)a.Size / (a.Size + b.Size)))
{
a.right = joinLR(a.right, b);
a.UpdateSize();
return(a);
}
else
{
b.left = joinLR(a, b.left);
b.UpdateSize();
return(b);
}
}