二叉树算法python实现：
1.添加节点
2.广度优先遍历
3.深度优先遍历：先序遍历，中序遍历，后序遍历
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# -*- codding:utf-8 -*-
class Node(object):
"""节点"""
def __init__(self,item):
self.elem = item
self.lchild = None
self.rchild = None
class Tree(object):
"""二叉树"""
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 bread_travel(self):
"""广度遍历"""
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 pre_travel(self,node):
"""前序遍历"""
if node is None:
return
print(node.elem,end = " ")
self.pre_travel(node.lchild)
self.pre_travel(node.rchild)
def mid_travel(self,node):
"""中序遍历"""
if node is None:
return
self.mid_travel(node.lchild)
print(node.elem,end = " ")
self.mid_travel(node.rchild)
def post_travel(self,node):
"""后序遍历"""
if node is None:
return
self.post_travel(node.lchild)
self.post_travel(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.bread_travel()
print(" ")
tree.pre_travel(tree.root)
print(" ")
tree.mid_travel(tree.root)
print(" ")
tree.post_travel(tree.root)
# 0 1 2 3 4 5 6 7 8 9 层次遍历
# 0 1 3 7 8 4 9 2 5 6 前序遍历
# 7 3 8 1 9 4 0 5 2 6 中序遍历
# 7 8 3 9 4 1 5 6 2 0 后序遍历
