二叉树及树的遍历

# 1.简单版

# 二叉树的搜索也可以分DFS和BFS 分别可以用栈和队列实现，也可以递归实现

from collections import deque

class BiTreeNode:
    def __init__(self, data):
        self.data = data
        self.lchild = None
        self.rchild = None

a = 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 = f

root = e

def 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):
    q = deque()
    q.append(root)
    while len(q) > 0:
        node = q.popleft()
        print(node.data, end='')
        if node.lchild:
            q.append(node.lchild)
        if node.rchild:
            q.append(node.rchild)

level_order(root)

# 2.升级版
class BTNode(object):
    def __init__(self, key=None, lchild=None, rchild=None):
        self.key = key
        self.lchild = lchild
        self.rchild = rchild


class BiTree(object):
    def __init__(self, data_list):
        # 初始化即将传入的列表的迭代器
        self.it = iter(data_list)

    def createBiTree(self, bt=None):
        try:
            # 步进获取下一个元素
            next_data = next(self.it)
            # 如果当前列表元素为'#', 则认为其为 None
            if next_data is "#":
                bt = None
            else:
                bt = BTNode(next_data)
                bt.lchild = self.createBiTree(bt.lchild)
                bt.rchild = self.createBiTree(bt.rchild)
        except Exception as e:
            print(e)

        return bt

    # 先序遍历函数
    def preOrderTrave(self, bt):
        if bt is not None:
            print(bt.key, end=" ")
            self.preOrderTrave(bt.lchild)
            self.preOrderTrave(bt.rchild)

    # 中序遍历函数
    def inOrderTrave(self, bt):
        if bt is not None:
            self.inOrderTrave(bt.lchild)
            print(bt.key, end=" ")
            self.inOrderTrave(bt.rchild)

    # 后序遍历函数
    def postOrderTrave(self, bt):
        if bt is not None:
            self.postOrderTrave(bt.lchild)
            self.postOrderTrave(bt.rchild)
            print(bt.key, end=" ")

    # 综合打印
    def printTrave(self, bt):
        print("先序遍历: ", end="")
        self.preOrderTrave(bt)
        print('
')
        print("中序遍历: ", end="")
        self.inOrderTrave(bt)
        print('
')
        print("后序遍历: ", end="")
        self.postOrderTrave(bt)
        print('
')


data = input("Please input the node value: ")
data_list = list(data)

btree = BiTree(data_list)
root = btree.createBiTree()
btree.printTrave(root)

# Please input the node value: abd#g###ce##fh###
# 先序遍历: a b d g c e f h
#
# 中序遍历: d g b a e c h f
#
# 后序遍历: g d b e h f c a