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AVLTree.py
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executable file
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""" Dictionary and searching
"""
from BiTree1 import BiTNode
from Assoc import Assoc
from DictBTree import DictBTree
# 支持动态操作的排序树： AVL 二叉树和树
class AVLNode(BiTNode):
def __init__(self, data):
BiTNode.__init__(self, data)
self.bf = 0
class DictAVL(DictBTree):
def __init__(self):
self._root = None
@staticmethod
def LL(a, b):
a.left = b.right
b.right = a
a.bf = b.bf = 0
return b
@staticmethod
def RR(a, b):
a.right = b.left
b.left = a
a.bf = b.bf = 0
return b
@staticmethod
def LR(a, b):
c = b.right
a.left, b.right = c.right, c.left
c.left, c.right = b, a
if c.bf == 0: # c 本身就是插入结点
a.bf = b.bf = 0
elif c.bf == 1: # 新结点在 c 左子树
a.bf = -1;
b.bf = 0
else: # 新结点在 c 右子树
a.bf = 0;
b.bf = 1
c.bf = 0;
return c;
def RL(a, b):
c = b.left
a.right, b.left = c.left, c.right
c.left, c.right = a, b
if c.bf == 0: # c 本身就是插入结点
a.bf = 0;
b.bf = 0
elif c.bf == 1: # 新结点在 c 的左子树
a.bf = 0;
b.bf = -1
else: # 新结点在 c 的右子树
a.bf = 1;
b.bf = 0
c.bf = 0
return c
def insert(self, key, value):
a = p = self._root
if a is None:
self._root = AVLNode(Assoc(key, value));
return
pa = q = None # 维持 pa, q 为 a, p 的父结点
while p is not None: # 确定插入位置及最小非平衡子树
if key == p.data.key: # key存在，修改关联值
p.data.value = value;
return
if p.bf != 0: pa, a = q, p # 已知最小非平衡子树
q = p
if key < p.data.key:
p = p.left
else:
p = p.right
# q 是插入点的父结点，parent，a 记录最小非平衡子树
node = AVLNode(Assoc(key, value))
if key < q.data.key:
q.left = node # 作为左子结点
else:
q.right = node # 或右子结点
# 新结点已插入，a 是最小不平衡子树
if key < a.data.key: # 新结点在 a 的左子树
p = b = a.left;
d = 1
else: # 新结点在 a 的右子树
p = b = a.right;
d = -1 # d记录新结点在a哪棵子树
# 修改 b 到新结点路上各结点的BF值，b 为 a 的子结点
while p != node: # node 一定存在，不用判断 p 空
if key < p.data.key: # p 的左子树增高
p.bf = 1;
p = p.left
else: # p的右子树增高
p.bf = -1;
p = p.right
if a.bf == 0: a.bf = d; return # a原BF为0，不会失衡
if a.bf == -d: a.bf = 0; return # 新结点在较低子树里
# 新结点在较高子树，失衡，必须调整
if d == 1: # 新结点在 a 的左子树
if b.bf == 1:
b = DictAVL.LL(a, b) # LL 调整
else:
b = DictAVL.LR(a, b) # LR 调整
else: # 新结点在 a 的右子树
if b.bf == -1:
b = DictAVL.RR(a, b) # RR 调整
else:
b = DictAVL.RL(a, b) # RL 调整
if pa is None:
self._root = b # 原 a 为树根
else:
if pa.left == a:
pa.left = b
else:
pa.right = b
def delete(self, key):
return
def print(self):
for entry in self.inorder():
print(entry.key, entry.value)
def depth(self):
def depth0(t):
if t is None: return 0
return max(depth0(t.left),
depth0(t.right)) + 1
return depth0(self._root)
# END class
def build_AVLTree(entries):
dic = DictAVL()
for k, v in entries:
dic.insert(k, v)
return dic
def build_random_AVL(n):
dic = DictAVL()
for i in range(n):
dic.insert(randint(1, n * 2), randint(1, 100))
return dic
if __name__ == '__main__':
from random import randint
## dic1 = build_random_AVL(20)
## for entry in dic1.inorder():
## print(entry.key, entry.value)
dic2 = DictAVL()
for i in range(15): # 15 entries with increasing keys
dic2.insert(i, i * i)
print(dic2.depth())
for entry in dic2.inorder():
print(entry.key, entry.value)
## dic3 = build_random_AVL(1000)
## print(dic3.depth())
##
## dic4 = DictAVL()
## for i in range(1000): # 1000 entries with increasing keys
## dic4.insert(i, i*i)
## print(dic4.depth())
pass