起因：
最近看到了一個python3的筆試題目，說是實現一個單向鏈表，並實現反轉方法。
說心裏話，看到這樣的題目，很無語。因爲我覺得這應該是C語言做的事情，但是仔細一想，興許這道題是爲了考察面試者的算法能力呢？所以就自己實現了一下，順便練習了一下pytest模塊的使用。
talk is cheap,show me the code
#! /usr/bin/python3
# -*- coding:utf-8 -*-
# file: linklist.py
# author: wangchenxi
# mail: [email protected]
# brief:
# version: 0.1.00
# Create Time:2019-11-12 17:03:51
# Last Update: 2019-11-13 00時14分52秒
class Node(object):
def __init__(self, val=None, *args, **kwarg):
self.value = val
self.next = None
class LinkList(object):
def __init__(self, *args, **kwarg):
self.__head = None
def __len__(self):
size = 0
t = self.__head
while t:
t = t.next
size += 1
return size
def tolist(self):
t = self.__head
index = 0
ret = []
while t:
ret.append(t.value)
t = t.next
index += 1
return ret
def fromlist(self, l):
n = 0
length = len(l)
self.clear()
while n < length:
self.append(Node(l[n]))
n += 1
def travel(self):
print(self.tolist())
def push(self, n):
if self.__head:
n.next = self.__head
self.__head = n
else:
self.__head = n
def append(self, n):
if not self.__head:
self.__head = n
return None
index = 0
np = self.__head
while np:
index += 1
pre = np
np = np.next
pre.next = n
def insert(self, pos, n):
if not pos:
return self.push(n)
if pos > len(self)-1:
return self.append(n)
t = pos
tn = self.__head
fn = tn
while t:
fn = tn
tn = tn.next
t -= 1
n.next = tn
fn.next = n
def pop(self, index=0):
if index > len(self) - 1:
return
dn = self.__head
fn = None
while index:
fn = dn
dn = dn.next
index -= 1
else:
if not fn:
nn = self.__head.next
self.__head.next = None
ret = self.__head
self.__head = nn
else:
nn = dn.next
dn.next = None
ret = dn
fn.next = nn
return ret
def delete(self, index=0):
self.pop(index)
def clear(self):
while len(self):
self.delete()
def update(self, pos, val):
if pos > len(self) - 1:
return
sn = self.__head
while pos:
sn = sn.next
pos -= 1
else:
sn.value = val
def index(self, val):
sn = self.__head
ind = 0
while sn and sn.value != val:
ind += 1
sn = sn.next
if sn:
return ind
def reverse(self):
_ = self.tolist()
_ = _[-1::-1]
self.fromlist(_)
def myreverse(self):
length = len(self)
if length < 2:
return
ind = 0
last = length - 1
while ind < length:
ret = self.pop(last)
self.insert(ind, ret)
ind += 1
pytest 模塊測試
#! /usr/bin/python3
# -*- coding:utf-8 -*-
# file: test_linklist.py
# author: wangchenxi
# mail: [email protected]
# brief:
# version: 0.1.00
# Create Time:2019-11-12 21:17:56
# Last Update: 2019-11-13 00時13分09秒
from linklist import Node, LinkList
def test_append():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
assert var_l.tolist() == r
def test_insert():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
var_l.insert(3, Node(20))
r.insert(3, 20)
assert var_l.tolist() == r
def test_delete():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
var_l.delete()
r.pop(0)
assert var_l.tolist() == r
def test_delete1():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
var_l.delete(3)
r.pop(3)
assert var_l.tolist() == r
def test_clear():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
var_l.clear()
r.clear()
assert var_l.tolist() == r
def test_update():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
var_l.update(4, 100)
r[4] = 100
assert var_l.tolist() == r
def test_index():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
assert var_l.index(6) == r.index(6)
def test_reverse():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
var_l.reverse()
r = r[-1::-1]
assert var_l.tolist() == r
def test_myreverse():
var_l = LinkList()
r = list()
for i in range(10):
var_l.append(Node(i))
r.append(i)
var_l.myreverse()
r = r[-1::-1]
assert var_l.tolist() == r
運行測試案例
pip3 install pytest
pytest -v test_linklist.py
測試案例執行結果
============================================================ test session starts ============================================================
platform linux -- Python 3.6.9, pytest-5.2.2, py-1.8.0, pluggy-0.13.0 -- /usr/bin/python3
cachedir: .pytest_cache
rootdir: /home/wangchenxi/for_find_work/datastruct
plugins: pep8-1.0.6
collected 9 items
test_linklist.py::test_append PASSED [ 11%]
test_linklist.py::test_insert PASSED [ 22%]
test_linklist.py::test_delete PASSED [ 33%]
test_linklist.py::test_delete1 PASSED [ 44%]
test_linklist.py::test_clear PASSED [ 55%]
test_linklist.py::test_update PASSED [ 66%]
test_linklist.py::test_index PASSED [ 77%]
test_linklist.py::test_reverse PASSED [ 88%]
test_linklist.py::test_myreverse PASSED [100%]
============================================================= 9 passed in 0.05s =============================================================