Python数据结构之二叉树

本来打算一个学期分别用C++、Python、Java实现数据结构，看来要提前了

这个是Python版本，我写的数据结构尽量保持灵活性，本文bt1是一般的插入法建立二叉树结构，bt2就是可以任意输入，至于树的高度的递归和非递归实现等等，在C++里实现过就不再重复。

#Date     : 2013-9-12
#Author   : DVD0423
#Function : 二叉树

class Node:
    def __init__(self, value = None, left = None, right = None):
        self.value = value
        self.left = left
        self.right = right
    def visit(self):
        print(self.value)

class BTree:
    def __init__(self, root = Node()):
        self.root = root

    def CreateBTree(self, _list = []):
        #层序遍历，产生二叉树结构
        length = len(_list)
        node = []
        for i in range(length):
            node.append(Node())
            node[i].value = _list[i]
        front = 0
        rear = 0
        while(rear != length):
            rear = rear + 1
            if rear >= length:
                break
            node[front].left = node[rear]
            rear = rear + 1
            if rear >= length:
                break
            node[front].right = node[rear]
            front = front + 1
        #下面这句没有必要，因为初始化就是None,但是逻辑上要有
        while(front != length):
            node[front].left = None
            node[front].right = None
            front = front + 1
        self.root = node[0]

    def Traverse(self, method):
        def PostOrder(node):

            if node:
                PostOrder(node.left)
                PostOrder(node.right)
                node.visit()

        def InOrder(node):
            if node:
                InOrder(node.left)
                node.visit()
                InOrder(node.right)

        def PreOrder(node):
            if node:
                node.visit()
                PreOrder(node.left)
                PreOrder(node.right)

        def NoRecTraverse(node):
            ls = []
            while True:
                if node:
                    ls.append(node)
                    node.visit()
                    node = node.left
                else:
                    if len(ls) != 0:
                        node = ls.pop()
                    node = node.right
                    if len(ls) == 0 and node == None:
                        break

        if method is 1:
            print("后序遍历")
            PostOrder(self.root)
        elif method is 2:
            print("中序遍历")
            InOrder(self.root)
        elif method is 3:
            print("前序遍历")
            PreOrder(self.root)
        else:
            print("非递归先序遍历")
            NoRecTraverse(self.root)
def InputInt():
    seq = []
    while True:
        ch = input()
        if ch is 'e':
            break
        seq.append(int(ch))
    return seq    

if __name__ == '__main__':
    #两种方式建立二叉树
    print("二叉树1：")
    node3 = Node(3)
    node2 = Node(2)
    node1 = Node(1, node2, node3)
    bt1 = BTree(node1)
    bt1.Traverse(4)

    print("二叉树2：")
    ls = InputInt()
    bt2 = BTree()
    bt2.CreateBTree(ls)
    bt2.Traverse(4)