2019.9.28-二叉树的先序、中序、后序遍历(代码)

# coding:utf-8

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

class Tree(object):
"""二叉樹"""
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):
"""廣度遍歷"""
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):
"""先序遍歷"""
if node is None:
return
print(node.elem, end=" ")
self.preorder(node.lchild)
self.preorder(node.rchild)

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

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

if __name__ == "__main__":
tree = Tree()
tree.add(0)
tree.add(1)
tree.add(2)
tree.add(3)
tree.add(4)
tree.add(5)
tree.add(6)
tree.add(7)
tree.add(8)
tree.add(9)
tree.breadth_travel()
print(" ")
tree.preorder(tree.root)
print(" ")
tree.inorder(tree.root)
print(" ")
tree.postorder(tree.root)
print(" ")

 执行结果

2019.9.28-二叉树的先序、中序、后序遍历(代码)

原文：https://www.cnblogs.com/lishuide/p/11605059.html