2023-06-21 12:46:23 -04:00

831 lines
26 KiB
C#

using System;
using System.Collections;
namespace System.util.collections
{
/// <summary>
/// k_Tree is a red-black balanced search tree (BST) implementation.
/// Complexity of find, insert and erase operations is near O(lg n).
/// </summary>
public class k_Tree : ISortedMap
{
#region k_Node Implementation
private class k_Node
{
private object mk_Key;
private object mk_Value;
private bool mb_Red;
public k_Node mk_Left, mk_Right, mk_Parent; // public to simplify fixup & clone (passing by ref)
public k_Node(object ak_Key, object ak_Value, k_Node ak_Parent)
{
mk_Key = ak_Key;
mk_Value = ak_Value;
mk_Parent = ak_Parent;
mb_Red = true;
}
public object Key
{
get { return mk_Key; }
}
public object Value
{
get { return mk_Value; }
set { mk_Value = value; }
}
public DictionaryEntry Item
{
get { return new DictionaryEntry(mk_Key, mk_Value); }
}
public bool Red
{
get { return mb_Red; }
set { mb_Red = value; }
}
public static void SwapItems(k_Node ak_A, k_Node ak_B)
{
object lk_Tmp = ak_A.mk_Key;
ak_A.mk_Key = ak_B.mk_Key;
ak_B.mk_Key = lk_Tmp;
lk_Tmp = ak_A.mk_Value;
ak_A.mk_Value = ak_B.mk_Value;
ak_B.mk_Value = lk_Tmp;
}
}
#endregion
#region k_NodeIterator Implementation
private class k_NodeIterator : k_Iterator
{
private readonly k_Tree mk_Tree;
private k_Node mk_Current;
public k_NodeIterator(k_Tree ak_Tree, k_Node ak_Node)
{
mk_Tree = ak_Tree;
mk_Current = ak_Node;
}
public override object Current
{
get
{
if (mk_Current == null)
throw new k_InvalidPositionException();
return mk_Current.Item;
}
set
{
DictionaryEntry lr_Entry = (DictionaryEntry)value;
if (mk_Tree.mk_Comparer.Compare(lr_Entry.Key, mk_Current.Key) != 0)
throw new ArgumentException("Key values must not be changed.");
mk_Current.Value = lr_Entry.Value;
}
}
public override object Collection
{
get { return mk_Tree; }
}
public override void Move(int ai_Count)
{
k_Node lk_NewPos = mk_Current;
if (ai_Count > 0)
{
while (ai_Count-- > 0)
{
if (lk_NewPos == null)
throw new InvalidOperationException("Tried to moved beyond end element.");
lk_NewPos = k_Tree.Next(lk_NewPos);
}
}
else
{
while (ai_Count++ < 0)
{
if (lk_NewPos == null)
lk_NewPos = mk_Tree.mk_Right;
else
lk_NewPos = k_Tree.Previous(lk_NewPos);
if (lk_NewPos == null)
throw new InvalidOperationException("Tried to move before first element.");
}
}
mk_Current = lk_NewPos;
}
public override int Distance(k_Iterator ak_Iter)
{
k_NodeIterator lk_Iter = ak_Iter as k_NodeIterator;
if (lk_Iter == null || !object.ReferenceEquals(lk_Iter.Collection, this.Collection))
throw new ArgumentException("Cannot determine distance of iterators belonging to different collections.");
k_Iterator lk_End = mk_Tree.End;
int li_KeyDiff;
if (this == lk_End || ak_Iter == lk_End)
li_KeyDiff = (this == lk_End && this != ak_Iter) ? 1 : 0;
else
li_KeyDiff = mk_Tree.mk_Comparer.Compare(mk_Current.Key, lk_Iter.mk_Current.Key);
if (li_KeyDiff <= 0)
{
int li_Diff = 0;
k_Iterator lk_Bck = this.Clone();
for (; lk_Bck != ak_Iter && lk_Bck != lk_End; lk_Bck.Next())
--li_Diff;
if (lk_Bck == ak_Iter)
return li_Diff;
}
if (li_KeyDiff >= 0)
{
int li_Diff = 0;
k_Iterator lk_Fwd = ak_Iter.Clone();
for (; lk_Fwd != this && lk_Fwd != lk_End; lk_Fwd.Next())
++li_Diff;
if (lk_Fwd == this)
return li_Diff;
}
throw new Exception("Inconsistent state. Concurrency?");
}
public override bool Equals(object ak_Obj)
{
k_NodeIterator lk_Iter = ak_Obj as k_NodeIterator;
if (lk_Iter == null)
return false;
return object.ReferenceEquals(mk_Current, lk_Iter.mk_Current);
}
public override int GetHashCode()
{
if (mk_Current == null)
return mk_Tree.GetHashCode();
return mk_Current.GetHashCode();
}
public override k_Iterator Clone()
{
return new k_NodeIterator(mk_Tree, mk_Current);
}
internal k_Node Node
{
get { return mk_Current; }
}
}
private class k_PinnedNodeIterator : k_NodeIterator
{
public k_PinnedNodeIterator(k_Tree ak_Tree, k_Node ak_Node)
: base(ak_Tree, ak_Node)
{
}
public override void Move(int ai_Count)
{
throw new k_IteratorPinnedException();
}
}
#endregion
private k_Node mk_Head, mk_Left, mk_Right;
private k_Iterator mk_End;
private int mi_Count;
private IComparer mk_Comparer;
private bool mb_AllowDuplicateKeys;
public k_Tree()
: this(false)
{
}
public k_Tree(bool ab_AllowDuplicateKeys)
: this(ab_AllowDuplicateKeys, System.Collections.Comparer.Default)
{
}
public k_Tree(bool ab_AllowDuplicateKeys, IComparer ak_Comparer)
{
mb_AllowDuplicateKeys = ab_AllowDuplicateKeys;
mk_Comparer = ak_Comparer;
mk_End = new k_PinnedNodeIterator(this, null);
}
// IContainer Members
public k_Iterator Begin
{
get
{
if (mi_Count == 0)
return this.End;
return new k_NodeIterator(this, mk_Left);
}
}
public k_Iterator End
{
get { return mk_End; }
}
public bool IsEmpty
{
get { return (mi_Count == 0); }
}
public k_Iterator Find(object ak_Value)
{
DictionaryEntry lr_Item = (DictionaryEntry)ak_Value;
k_Node lk_Found = FindInternal(mk_Head, lr_Item.Key);
if (lk_Found != null && mk_Comparer.Compare(lk_Found.Value, lr_Item.Value) == 0)
return new k_NodeIterator(this, lk_Found);
return this.End;
}
public k_Iterator Erase(k_Iterator ak_Where)
{
//System.Diagnostics.Debug.Assert(object.ReferenceEquals(this, ak_Where.Collection), "Iterator does not belong to this tree.");
k_Iterator lk_Successor = ak_Where + 1;
RemoveNode(((k_NodeIterator)ak_Where).Node);
return lk_Successor;
}
public k_Iterator Erase(k_Iterator ak_First, k_Iterator ak_Last)
{
if (ak_First == this.Begin && ak_Last == this.End)
{
Clear();
return ak_Last.Clone();
}
k_Iterator lk_Current = ak_First;
while (lk_Current != ak_Last)
lk_Current = Erase(lk_Current);
return lk_Current;
}
// IMap Members
public void Add(DictionaryEntry ar_Item)
{
Add(ar_Item.Key, ar_Item.Value);
}
public k_Iterator FindKey(object ak_Key)
{
return new k_NodeIterator(this, FindInternal(mk_Head, ak_Key));
}
public void Insert(k_Iterator ak_SrcBegin, k_Iterator ak_SrcEnd)
{
for (k_Iterator lk_Iter = ak_SrcBegin.Clone(); lk_Iter != ak_SrcEnd; lk_Iter.Next())
Add((DictionaryEntry)lk_Iter.Current);
}
// ISortedMap Members
public IComparer Comparer
{
get { return mk_Comparer; }
}
public k_Iterator LowerBound(object ak_Key)
{
k_Node lk_Node = mk_Head;
k_Node lk_Found = null;
while (lk_Node != null)
{
if (mk_Comparer.Compare(lk_Node.Key, ak_Key) < 0)
lk_Node = lk_Node.mk_Right;
else
{
lk_Found = lk_Node;
lk_Node = lk_Node.mk_Left;
}
}
return new k_NodeIterator(this, lk_Found);
}
public k_Iterator UpperBound(object ak_Key)
{
k_Node lk_Node = mk_Head;
k_Node lk_Found = null;
while (lk_Node != null)
{
if (mk_Comparer.Compare(lk_Node.Key, ak_Key) > 0)
{
lk_Found = lk_Node;
lk_Node = lk_Node.mk_Left;
}
else
lk_Node = lk_Node.mk_Right;
}
return new k_NodeIterator(this, lk_Found);
}
#region IDictionary Members
public void Add(object ak_Key, object ak_Value)
{
Insert(ref mk_Head, null, ak_Key, ak_Value, false);
mk_Head.Red = false;
++mi_Count;
}
public void Clear()
{
mi_Count = 0;
mk_Head = null;
mk_Left = null;
mk_Right = null;
}
public bool Contains(object ak_Key)
{
return (FindInternal(mk_Head, ak_Key) != null);
}
public IDictionaryEnumerator GetEnumerator()
{
return new k_IteratorDictEnumerator(this.Begin, this.End);
}
public void Remove(object ak_Key)
{
RemoveNode(FindInternal(mk_Head, ak_Key));
}
public bool IsFixedSize
{
get { return false; }
}
public bool IsReadOnly
{
get { return false; }
}
public object this[object ak_Key]
{
get
{
k_Node lk_Node = FindInternal(mk_Head, ak_Key);
if (lk_Node == null)
return null;
return lk_Node.Value;
}
set
{
k_Node lk_Node = FindInternal(mk_Head, ak_Key);
if (lk_Node == null)
Add(new DictionaryEntry(ak_Key, value));
else
lk_Node.Value = value;
}
}
public ICollection Keys
{
get
{
int i=0;
object[] lk_Keys = new object[mi_Count];
foreach (DictionaryEntry lr_Entry in this)
lk_Keys[i++] = lr_Entry.Key;
return lk_Keys;
}
}
public ICollection Values
{
get
{
int i=0;
object[] lk_Values = new object[mi_Count];
foreach (DictionaryEntry lr_Entry in this)
lk_Values[i++] = lr_Entry.Value;
return lk_Values;
}
}
#endregion
#region ICollection Members
public void CopyTo(Array ak_Array, int ai_Index)
{
foreach (DictionaryEntry lr_Entry in this)
ak_Array.SetValue(lr_Entry, ai_Index++);
}
public int Count
{
get { return mi_Count; }
}
public bool IsSynchronized
{
get { return false; }
}
public object SyncRoot
{
get { return this; }
}
#endregion
#region IEnumerable Members
IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return new k_IteratorEnumerator(this.Begin, this.End);
}
#endregion
#region ICloneable Members
public object Clone()
{
k_Tree lk_Clone = new k_Tree(mb_AllowDuplicateKeys, mk_Comparer);
lk_Clone.mi_Count = mi_Count;
CloneRecursive(mk_Head, null, ref lk_Clone.mk_Head);
lk_Clone.mk_Left = k_Tree.LeftMost(lk_Clone.mk_Head);
lk_Clone.mk_Right = k_Tree.RightMost(lk_Clone.mk_Head);
return lk_Clone;
}
#endregion
private void CloneRecursive(k_Node ak_Node, k_Node ak_Parent, ref k_Node ak_Link)
{
if (ak_Node == null)
return;
ak_Link = new k_Node(ak_Node.Key, ak_Node.Value, ak_Parent);
ak_Link.Red = ak_Node.Red;
CloneRecursive(ak_Node.mk_Left, ak_Link, ref ak_Link.mk_Left);
CloneRecursive(ak_Node.mk_Right, ak_Link, ref ak_Link.mk_Right);
}
private bool IsRed(k_Node ak_Node)
{
return (ak_Node != null && ak_Node.Red);
}
private k_Node FindInternal(k_Node ak_Node, object ak_Key)
{
while (ak_Node != null)
{
int li_Diff = mk_Comparer.Compare(ak_Key, ak_Node.Key);
if (li_Diff == 0)
return ak_Node;
ak_Node = (li_Diff < 0) ? ak_Node.mk_Left : ak_Node.mk_Right;
}
return null;
}
/// <summary>
/// Return leftmost node in subtree.
/// </summary>
/// <param name="ak_Node">Node where to start search</param>
/// <returns>Found node</returns>
private static k_Node LeftMost(k_Node ak_Node)
{
if (ak_Node == null)
return null;
while (ak_Node.mk_Left != null)
ak_Node = ak_Node.mk_Left;
return ak_Node;
}
/// <summary>
/// Return rightmost node in subtree.
/// </summary>
/// <param name="ak_Node">Node where to start search</param>
/// <returns>Found node</returns>
private static k_Node RightMost(k_Node ak_Node)
{
if (ak_Node == null)
return null;
while (ak_Node.mk_Right != null)
ak_Node = ak_Node.mk_Right;
return ak_Node;
}
private static k_Node Previous(k_Node ak_Node) // the next smaller
{
if (ak_Node.mk_Left != null)
return RightMost(ak_Node.mk_Left);
k_Node lk_Parent = ak_Node.mk_Parent;
while (lk_Parent != null && lk_Parent.mk_Left == ak_Node)
{
ak_Node = lk_Parent;
lk_Parent = lk_Parent.mk_Parent;
}
return lk_Parent;
}
private static k_Node Next(k_Node ak_Node)
{
if (ak_Node.mk_Right != null)
return LeftMost(ak_Node.mk_Right);
k_Node lk_Parent = ak_Node.mk_Parent;
while (lk_Parent != null && lk_Parent.mk_Right == ak_Node)
{
ak_Node = lk_Parent;
lk_Parent = lk_Parent.mk_Parent;
}
return lk_Parent;
}
private void RemoveNode(k_Node ak_Node)
{
if (ak_Node == null)
return;
if (ak_Node == mk_Head)
UnlinkNode(ref mk_Head);
else if (ak_Node == ak_Node.mk_Parent.mk_Right)
UnlinkNode(ref ak_Node.mk_Parent.mk_Right);
else
UnlinkNode(ref ak_Node.mk_Parent.mk_Left);
}
private void UnlinkNode(ref k_Node ak_Node)
{
bool lb_Red = ak_Node.Red;
k_Node lk_Erased = ak_Node;
k_Node lk_PatchNode = null;
if (ak_Node.mk_Right == null)
lk_PatchNode = ak_Node.mk_Left;
else if (ak_Node.mk_Left == null)
lk_PatchNode = ak_Node.mk_Right;
else
lk_PatchNode = ak_Node;
k_Node lk_PatchParent = null, lk_FixNode = null;
if (lk_PatchNode == null)
{
lk_PatchParent = ak_Node.mk_Parent;
ak_Node = null;
}
else if (lk_PatchNode != ak_Node)
{
lk_PatchNode.mk_Parent = ak_Node.mk_Parent;
ak_Node = lk_PatchNode;
lk_PatchParent = lk_PatchNode.mk_Parent;
}
else
{
// two subtrees
lk_PatchNode = RightMost(ak_Node.mk_Left);
if (lk_PatchNode.mk_Parent.mk_Right == lk_PatchNode)
lk_PatchNode.mk_Parent.mk_Right = lk_PatchNode.mk_Left;
else
lk_PatchNode.mk_Parent.mk_Left = lk_PatchNode.mk_Left;
lb_Red = lk_PatchNode.Red;
if (lk_PatchNode.mk_Left != null)
lk_PatchNode.mk_Left.mk_Parent = lk_PatchNode.mk_Parent;
lk_PatchParent = lk_PatchNode.mk_Parent;
lk_FixNode = lk_PatchNode.mk_Left;
k_Node.SwapItems(ak_Node, lk_PatchNode);
// ensure that mk_Left and/or mk_Right are corrected after unlink
lk_Erased = lk_PatchNode;
}
if (!lb_Red && lk_PatchParent != null)
{
// erased node was black link - rebalance the tree
while (!IsRed(lk_FixNode) && lk_FixNode != mk_Head)
{
if (lk_PatchParent.mk_Left != null || lk_PatchParent.mk_Right != null)
{
if (lk_PatchParent.mk_Left == lk_FixNode)
{
// fixup right subtree
k_Node lk_Node = lk_PatchParent.mk_Right;
if (IsRed(lk_Node))
{
lk_Node.Red = false;
lk_PatchParent.Red = true;
RotateLeft(lk_PatchParent);
lk_Node = lk_PatchParent.mk_Right;
}
if (lk_Node != null)
{
if (!IsRed(lk_Node.mk_Left) && !IsRed(lk_Node.mk_Right))
lk_Node.Red = true;
else
{
if (!IsRed(lk_Node.mk_Right))
{
lk_Node.Red = true;
lk_Node.mk_Left.Red = false;
RotateRight(lk_Node);
lk_Node = lk_PatchParent.mk_Right;
}
lk_Node.Red = lk_PatchParent.Red;
lk_PatchParent.Red = false;
lk_Node.mk_Right.Red = false;
RotateLeft(lk_PatchParent);
break;
}
}
}
else
{
// fixup leftsubtree
k_Node lk_Node = lk_PatchParent.mk_Left;
if (IsRed(lk_Node))
{
lk_Node.Red = false;
lk_PatchParent.Red = true;
RotateRight(lk_PatchParent);
lk_Node = lk_PatchParent.mk_Left;
}
if (lk_Node != null)
{
if (!IsRed(lk_Node.mk_Left) && !IsRed(lk_Node.mk_Right))
lk_Node.Red = true;
else
{
if (!IsRed(lk_Node.mk_Left))
{
lk_Node.Red = true;
lk_Node.mk_Right.Red = false;
RotateLeft(lk_Node);
lk_Node = lk_PatchParent.mk_Left;
}
lk_Node.Red = lk_PatchParent.Red;
lk_PatchParent.Red = false;
lk_Node.mk_Left.Red = false;
RotateRight(lk_PatchParent);
break;
}
}
}
}
lk_FixNode = lk_PatchParent;
lk_PatchParent = lk_PatchParent.mk_Parent;
}
if (lk_FixNode != null)
lk_FixNode.Red = false;
}
--mi_Count;
if (object.ReferenceEquals(lk_Erased, mk_Right))
mk_Right = k_Tree.RightMost(mk_Head);
if (object.ReferenceEquals(lk_Erased, mk_Left))
mk_Left = k_Tree.LeftMost(mk_Head);
}
private void Insert(ref k_Node ak_Node, k_Node ak_Parent, object ak_Key, object ak_Value, bool ab_RightMove)
{
if (ak_Node == null)
{
ak_Node = new k_Node(ak_Key, ak_Value, ak_Parent);
if (object.ReferenceEquals(ak_Parent, mk_Right) && (ak_Parent == null || ab_RightMove))
mk_Right = ak_Node;
if (object.ReferenceEquals(ak_Parent, mk_Left) && (ak_Parent == null || !ab_RightMove))
mk_Left = ak_Node;
return;
}
if (IsRed(ak_Node.mk_Left) && IsRed(ak_Node.mk_Right))
{
ak_Node.Red = true;
ak_Node.mk_Left.Red = false;
ak_Node.mk_Right.Red = false;
}
int li_Diff = mk_Comparer.Compare(ak_Key, ak_Node.Key);
if (!mb_AllowDuplicateKeys && li_Diff == 0)
throw new ArgumentException("An element with the same key already exists in the tree.");
if (li_Diff < 0)
{
Insert(ref ak_Node.mk_Left, ak_Node, ak_Key, ak_Value, false);
if (IsRed(ak_Node) && IsRed(ak_Node.mk_Left) && ab_RightMove)
ak_Node = RotateRight(ak_Node);
if (IsRed(ak_Node.mk_Left) && IsRed(ak_Node.mk_Left.mk_Left))
{
ak_Node = RotateRight(ak_Node);
ak_Node.Red = false;
ak_Node.mk_Right.Red = true;
}
}
else
{
Insert(ref ak_Node.mk_Right, ak_Node, ak_Key, ak_Value, true);
if (IsRed(ak_Node) && IsRed(ak_Node.mk_Right) && !ab_RightMove)
ak_Node = RotateLeft(ak_Node);
if (IsRed(ak_Node.mk_Right) && IsRed(ak_Node.mk_Right.mk_Right))
{
ak_Node = RotateLeft(ak_Node);
ak_Node.Red = false;
ak_Node.mk_Left.Red = true;
}
}
}
/*
A right rotation: ak_Node.Left takes old position of ak_Node.
Makes the old root the right subtree of the new root.
5 2
2 7 -> 1 5
1 3 6 8 3 7
6 8
*/
private k_Node RotateRight(k_Node ak_Node)
{
k_Node lk_Tmp = ak_Node.mk_Left;
lk_Tmp.mk_Parent = ak_Node.mk_Parent;
ak_Node.mk_Parent = lk_Tmp;
ak_Node.mk_Left = lk_Tmp.mk_Right;
if (ak_Node.mk_Left != null)
ak_Node.mk_Left.mk_Parent = ak_Node;
lk_Tmp.mk_Right = ak_Node;
// correct parent
if (lk_Tmp.mk_Parent == null)
mk_Head = lk_Tmp;
else if (lk_Tmp.mk_Parent.mk_Right == ak_Node)
lk_Tmp.mk_Parent.mk_Right = lk_Tmp;
else
lk_Tmp.mk_Parent.mk_Left = lk_Tmp;
return lk_Tmp;
}
/*
A left rotation: ak_Node.Right takes old position of ak_Node.
Makes the old root the left subtree of the new root.
5 7
2 7 -> 5 8
1 3 6 8 2 6
1 3
*/
private k_Node RotateLeft(k_Node ak_Node)
{
k_Node lk_Tmp = ak_Node.mk_Right;
lk_Tmp.mk_Parent = ak_Node.mk_Parent;
ak_Node.mk_Parent = lk_Tmp;
ak_Node.mk_Right = lk_Tmp.mk_Left;
if (ak_Node.mk_Right != null)
ak_Node.mk_Right.mk_Parent = ak_Node;
lk_Tmp.mk_Left = ak_Node;
// correct parent
if (lk_Tmp.mk_Parent == null)
mk_Head = lk_Tmp;
else if (lk_Tmp.mk_Parent.mk_Right == ak_Node)
lk_Tmp.mk_Parent.mk_Right = lk_Tmp;
else
lk_Tmp.mk_Parent.mk_Left = lk_Tmp;
return lk_Tmp;
}
}
}