# coding=utf-8
# treap(树堆)Python实现
import random
def preorder_tree_walk(node):
if node:
print node.key, node.priority
preorder_tree_walk(node.left)
preorder_tree_walk(node.right)
def left_rotate(tree, node):
node_right = node.right
if not node.p:
tree.root = node_right
elif node == node.p.left:
node.p.left = node_right
else:
node.p.right = node_right
node_right.p = node.p
node.right = node_right.left
if node_right.left:
node_right.left.p = node
node_right.left = node
node.p = node_right
def right_rotate(tree, node):
node_left = node.left
if not node.p:
tree.root = node_left
elif node == node.p.left:
node.p.left = node_left
else:
node.p.right = node_left
node_left.p = node.p
node.left = node_left.right
if node_left.right:
node_left.right.p = node
node_left.right = node
node.p = node_left
class TreapNode(object):
def __init__(self, key, priority):
self.key = key
self.priority = priority
self.left = None
self.right = None
self.p = None
class Treap(object):
def __init__(self):
self.root = None
def find(self, key):
temp_root = self.root
while temp_root:
if key < temp_root.key:
temp_root = temp_root.left
elif key > temp_root.key:
temp_root = temp_root.right
else:
return temp_root
return None
def insert(self, node):
temp_root = self.root
temp_node = None
while temp_root:
temp_node = temp_root
if node.key > temp_node.key:
temp_root = temp_root.right
elif node.key < temp_node.key:
temp_root = temp_root.left
else:
raise KeyError, "Error"
if not temp_node:
self.root = node
return
elif node.key < temp_node.key:
temp_node.left = node
node.p = temp_node
elif node.key > temp_node.key:
temp_node.right = node
node.p = temp_node
self.fixup(temp_node, node)
def fixup(self, father, child):
if father:
if child == father.left and child.priority < father.priority:
right_rotate(self, father)
elif child == father.right and child.priority < father.priority:
left_rotate(self, father)
self.fixup(father.p, father)
def delete(self, key):
node = self.root
while node:
if key < node.key:
node = node.left
elif key > node.key:
node = node.right
else:
break
if not node:
raise KeyError, "Error!"
flag = 1
while flag:
if not node.left:
if node.right:
node.right.p = node.p
if node.p:
if node == node.p.left:
node.p.left = node.right
else:
node.p.right = node.right
else:
self.root = node.right
flag = 0
elif not node.right:
if node.left:
node.left.p = node.p
if node.p:
if node == node.p.left:
node.p.left = node.left
else:
node.p.right = node.left
else:
self.root = node.left
flag = 0
else:
# 如果左右子节点均存在 那么把 priority 值大的放到根节点的位置上 网上给的是递归实现 那有没有可能可以递推实现呢？
# 答案是 有可能的
if node.left.priority < node.right.priority:
right_rotate(self, node)
else:
left_rotate(self, node)
def main():
number_list = (7, 4, 1, 8, 5, 2, 9, 6, 3)
tree = Treap()
for number in number_list:
priority = random.randint(1, 100)
node = TreapNode(number, priority)
tree.insert(node)
preorder_tree_walk(tree.root)
print '=========='
tree.delete(4)
preorder_tree_walk(tree.root)
if __name__ == '__main__':
main()
网上一些资料都是递归实现的插入和删除, Python由于没有按引用传递, 所以暂时没有想到好的办法来递归实现, 只好递推实现。
注:暂时没有时间写实现思路，等过一段时间补上
End.
