樹是數據結構中常用到的一種結構，其實現較棧和隊稍為復雜一些。若樹中的所有節點的孩子節點數量不超過2個，則該為一個二叉樹。
樹
“嵌套列表”表示樹
2017080815021788582607.png
20170808150217857149175.png
myTree = ['a', #root
['b', #left subtree
['d' [], []],
['e' [], []] ],
['c', #right subtree
['f' [], []],
[] ]
]
myTree = ['a', ['b', ['d',[],[]], ['e',[],[]] ], ['c', ['f',[],[]], []] ]
print(myTree)
print('left subtree = ', myTree[1])
print('root = ', myTree[0])
print('right subtree = ', myTree[2])
樹的根是myTree[0]，根的左子樹是myTree[1]，和右子樹是myTree[2]
二叉樹
20170808150217865294242.png
20170808150217881617379.png
20170808150217917424511.png
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Created by xuehz on 2017/8/8
#二叉樹
class Tree():
def __init__(self, leftjd=0, rightjd=0, data =0):
self.leftjd = leftjd
self.rightjd = rightjd
self.data = data
class Btree():
def __init__(self, base = 0):
self.base = base
def empty(self):
if self.base is 0:
return True
else:
return False
def qout(self, jd):
"""
前序遍歷 NLR 根左右
:param jd:
:return:
"""
if jd == 0:
return
print jd.data
self.qout(jd.leftjd) #遞歸調用
self.qout(jd.rightjd)
def mout(self,jd):
"""
中序遍歷 LNR 左根右
:param jd:
:return:
"""
if jd == 0:
return
self.qout(jd.leftjd)
print jd.data
self.qout(jd.rightjd)
def hout(self,jd):
"""
后序遍歷 LRN 左右根
:param jd:
:return:
"""
if jd ==0:
return
self.qout(jd.leftjd) # 遞歸調用
self.qout(jd.rightjd)
print jd.data
if __name__ == '__main__':
dj1 = Tree(data=8)
dj2 = Tree(data=9)
base = Tree(dj1, dj2, 7)# 根節點
x = Btree(base)
x.qout(x.base)
print '========'
x.mout(x.base)
print '========'
x.hout(x.base)
