0
我一直在嘗試實現splay樹，但迄今爲止沒有成功。以前我成功實現了二叉搜索樹和avl樹，並且由於splay tree是二叉搜索樹的變體，所以插入代碼和旋轉編碼是唯一的罰款。我面對的是每次節點inserted.This移動節點到根本的問題是我的代碼Splay樹插入實現中的問題
class SplayTree:
def __init__(self):
self.root = None
self.size = 0
def moveUp(self, currentNode):
if currentNode.parent:
if currentNode.parent.parent is not None:
#zig zag
if currentNode.isRightChild() and currentNode.parent.isLeftChild():
self.rotateLeft(currentNode.parent)
self.rotateRight(currentNode.parent)
elif currentNode.isLeftChild() and currentNode.parent.isRightChild():
self.rotateRight(currentNode.parent)
self.rotateLeft(currentNode.parent)
#zig zig
if currentNode.isLeftChild() and currentNode.parent.isLeftChild():
self.rotateRight(currentNode.parent.parent)
self.rotateRight(currentNode.parent)
elif currentNode.isRightChild() and currentNode.parent.isRightChild():
self.rotateLeft(currentNode.parent.parent)
self.rotateLeft(currentNode.parent)
self.moveUp(currentNode)
#zig
if currentNode.isLeftChild():
self.rotateRight(currentNode.parent)
elif currentNode.isRightChild():
self.rotateLeft(currentNode.parent)
self.moveUp(currentNode)
else:
return
def put(self,key,val):
if self.root:
self._put(key,val,self.root)
else:
self.root = TreeNode(key,val)
self.size += 1
def _put(self,key,val,currentNode):
if key < currentNode.key:
if currentNode.hasLeftChild():
self._put(key,val,currentNode.leftChild)
else:
currentNode.leftChild = TreeNode(key,val,parent=currentNode)
self.moveUp(currentNode.leftChild)
else:
if currentNode.hasRightChild():
self._put(key,val,currentNode.rightChild)
else:
currentNode.rightChild = TreeNode(key,val,parent=currentNode)
self.moveUp(currentNode.rightChild)
def __setitem__(self, key, value):
self.put(key,value)
def rotateLeft(self, rotRoot):
newRoot = rotRoot.rightChild
if newRoot.leftChild is not None:
rotRoot.rightChild = newRoot.leftChild
newRoot.leftChild.parent = rotRoot
# if subtree is at top or somewhere in between
# make connection between node and parent
newRoot.parent = rotRoot.parent
if rotRoot.parent is None:
self.root = newRoot
# make connection between parent and node
else:
if rotRoot.isLeftChild():
rotRoot.parent.leftChild = newRoot
else:
rotRoot.parent.rightChild = newRoot
newRoot.leftChild = rotRoot
rotRoot.parent = newRoot
def rotateRight(self, rotRoot):
newRoot = rotRoot.leftChild
if newRoot.rightChild is not None:
rotRoot.leftChild = newRoot.rightChild
newRoot.rightChild.parent = rotRoot
newRoot.parent = rotRoot.parent
if rotRoot.parent is None:
self.root = newRoot
else:
if rotRoot.isLeftChild():
rotRoot.parent.leftChild = newRoot
else:
rotRoot.parent.rightChild = newRoot
newRoot.rightChild = rotRoot
rotRoot.parent = newRoot
def inorder(self):
print("INORDER")
if self.root:
self._inorder(self.root)
print()
else:
return None
def _inorder(self,currentNode):
if currentNode:
self._inorder(currentNode.leftChild)
print(currentNode.key,end=" ")
self._inorder(currentNode.rightChild)
class TreeNode:
def __init__(self,key,val,left = None,right = None,parent = None):
self.key = key
self.payload = val
self.leftChild = left
self.rightChild = right
self.parent = parent
def hasLeftChild(self):
return self.leftChild
def hasRightChild(self):
return self.rightChild
def isLeftChild(self):
return self.parent and self.parent.leftChild == self
def isRightChild(self):
return self.parent and self.parent.rightChild == self
def isLeaf(self):
return not (self.leftChild or self.rightChild)
def hasAnyChildren(self):
return self.leftChild or self.rightChild
def hasBothChildren(self):
return self.leftChild and self.rightChild
st = SplayTree()
st[32] = "Cat"
st[55] = "Dog"
st[10] = "Lion"
st[41] = "Zebra"
st[19] = "Fox"
st[1] = "Wolf"
st[16] = "Tiger"
st[12] = "Pig"
st.inorder()
我覺得我爲moveUp（）方法就是事情的進展但是我似乎無法弄清楚究竟發生了什麼問題？
我覺得你的旋轉方法有點小錯誤。應該無條件地運行'rotateLeft'中的第一個'if'（和'rotateRight'中的等效行）中的'rotRoot.rightChild = newRoot.leftChild'行。否則，你可以從'rotRoot'連接到'newRoot'，它應該被'None'替代。 – Blckknght
@Blckknght這是一個很好的觀察。現在代碼正在運行，但給出了不正確的結果。最後添加的節點沒有進入根目錄！我重新檢查了moveUp（）代碼，似乎沒有發現任何可疑內容。 –
@Blckknght哦，現在它的工作正常......只是做了一些微小的調整。再次感謝！ –