Python算法——二叉树

一、二叉树

from collections import dequeclass BiTreeNode:def __init__(self, data):self.data = dataself.lchild = Noneself.rchild = Nonea = BiTreeNode('A')
b = BiTreeNode('B')
c = BiTreeNode('C')
d = BiTreeNode('D')
e = BiTreeNode('E')
f = BiTreeNode('F')
g = BiTreeNode('G')e.lchild = a
e.rchild = g
a.rchild = c
c.lchild = b
c.rchild = d
g.rchild = froot = edef pre_order(root):if root:print(root.data, end='')pre_order(root.lchild)pre_order(root.rchild)def in_order(root):if root:in_order(root.lchild)print(root.data, end='')in_order(root.rchild)def post_order(root):if root:post_order(root.lchild)post_order(root.rchild)print(root.data, end='')def level_order(root):queue = deque()queue.append(root)while len(queue) > 0:node = queue.popleft()print(node.data,end='')if node.lchild:queue.append(node.lchild)if node.rchild:queue.append(node.rchild)pre_order(root)
print("")
in_order(root)
print("")
post_order(root)
print("")
level_order(root)

        

        

class BiTreeNode:def __init__(self, data):self.data = dataself.lchild = Noneself.rchild = Noneclass BST:def __init__(self, li=None):self.root = Noneif li:self.root = self.insert(self.root, li[0])for val in li[1:]:self.insert(self.root, val)def insert(self, root, val):if root is None:root = BiTreeNode(val)elif val < root.data:root.lchild = self.insert(root.lchild, val)else:root.rchild = self.insert(root.rchild, val)return rootdef insert_no_rec(self, val):p = self.rootif not p:self.root = BiTreeNode(val)returnwhile True:if val < p.data:if p.lchild:p = p.lchildelse:p.lchild = BiTreeNode(val)breakelse:if p.rchild:p = p.rchildelse:p.rchild = BiTreeNode(val)breakdef query(self, root, val):if not root:return Falseif root.data == val:return Trueelif root.data > val:return self.query(root.lchild, val)else:return self.query(root.rchild, val)def query_no_rec(self, val):p = self.rootwhile p:if p.data == val:return Trueelif p.data > val:p = p.lchildelse:p = p.rchildreturn Falsedef in_order(self, root):if root:self.in_order(root.lchild)print(root.data, end=',')self.in_order(root.rchild)tree = BST()
for i in [1,5,9,8,7,6,4,3,2]:tree.insert_no_rec(i)
tree.in_order(tree.root)
#print(tree.query_no_rec(12))