python（五）二叉树

# coding:utf-8

import random


class Node(object):
    def __init__(self, item):
        self.elem = item
        self.lchild = None
        self.rchild = None

class Tree(object):
    def __init__(self):
        self.root = None

    def add(self, item):
        node = Node(item)
        if self.root is None:
            self.root = node
            return
        queue = [self.root]
        while queue:
            cur_node = queue.pop(0)
            if cur_node.lchild is None:
                cur_node.lchild = node
                return
            else:
                queue.append(cur_node.lchild)
            if cur_node.rchild is None:
                cur_node.rchild = node
                return
            else:
                queue.append(cur_node.rchild)

    def breadth_travel(self):
        if self.root is None:
            return
        queue = [self.root]
        while queue:
            cur_node = queue.pop(0)
            print(cur_node.elem, end=" ")
            if cur_node.lchild is not None:
                queue.append(cur_node.lchild)
            if cur_node.rchild is not None:
                queue.append(cur_node.rchild)

    def preorder(self, node):
        if node is None:
            return
        print(node.elem, end=" ")
        self.preorder(node.lchild)
        self.preorder(node.rchild)

    def inorder(self, node):
        if node is None:
            return
        self.inorder(node.lchild)
        print(node.elem, end=" ")
        self.inorder(node.rchild)

    def postorder(self, node):
        if node is None:
            return
        self.postorder(node.lchild)
        self.postorder(node.rchild)
        print(node.elem, end=" ")


if __name__ == "__main__":
    seq = list(range(1, 100))
    li = random.sample(seq, 20)
    tree = Tree()

    for j in range(0, 10):
        tree.add(random.choice(li))

    print("广度遍历")
    tree.breadth_travel()
    print("")

    print("先序遍历")
    tree.preorder(tree.root)
    print("")

    print("中序遍历")
    tree.inorder(tree.root)
    print("")

    print("后序遍历")
    tree.postorder(tree.root)
    print("")