PythonProblemSolving/RemoveNthNodeFromEnd.py at master · ebaumstarck/PythonProblemSolving · GitHub

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importunittest

classNode(object):
def__init__(self,data=None,next=None):
self.data=data
self.next=next

deflistToString(head):
s=''
p=head
whilep:
s+=str(p.data) +'->'
p=p.next
s+='NULL'
returns

deflistLength(head):
i=0
p=head
whilep:
p=p.next
i=i+1

returni

'''
 remove the nth node from end of the list
 1->2->3->4, n=2, return 1->2->4
'''
defRemoveNthNodeFromEnd(head,n):
'''
 Args: head node of the linked list,
 the nth node from the end of the list
 Return: the head of the linked list
 '''
p=head
q=head
ifn<=0orn>listLength(head):
raiseException("Invalid n")
elifn==listLength(head):
head=p.next
else:
whilen>=0:
q=q.next
n=n-1
whileq:
p=p.next
q=q.next

p.next=p.next.next

returnhead

defassertEquals(a, b):
ifa!=b:
raiseException("Values not equal: %s vs. %s"% (a, b))

defassertRaises(f, *args, **kwargs):
raised=False
try:
f(*args, **kwargs)
except:
raised=True
ifnotraised:
raiseException("Exception was not raised")

# printList(RemoveNthNodeFromEnd(head,4))
defGetTestList():
returnNode(1,Node(2,Node(3,Node(4))))
assertEquals("1->2->3->4->NULL", listToString(GetTestList()))
# assertEquals("1->2->3->4->NULL", listToString(RemoveNthNodeFromEnd(head, 0)))
# assertRaises(RemoveNthNodeFromEnd(head, 0))
assertRaises(RemoveNthNodeFromEnd, GetTestList(), 0)
assertEquals("1->2->3->NULL", listToString(RemoveNthNodeFromEnd(GetTestList(), 1)))
assertEquals("1->2->4->NULL", listToString(RemoveNthNodeFromEnd(GetTestList(), 2)))
assertEquals("1->3->4->NULL", listToString(RemoveNthNodeFromEnd(GetTestList(), 3)))
assertEquals("2->3->4->NULL", listToString(RemoveNthNodeFromEnd(GetTestList(), 4)))
assertRaises(RemoveNthNodeFromEnd, GetTestList(), 5)


classTestSequenceFunctions(unittest.TestCase):

defsetUp(self):
self.seq=range(10)

deftest_shuffle(self):
# make sure the shuffled sequence does not lose any elements
random.shuffle(self.seq)
self.seq.sort()
self.assertEqual(self.seq, range(10))

# should raise an exception for an immutable sequence
self.assertRaises(TypeError, random.shuffle, (1,2,3))

deftest_choice(self):
element=random.choice(self.seq)
self.assertTrue(elementinself.seq)

deftest_sample(self):
withself.assertRaises(ValueError):
random.sample(self.seq, 20)
forelementinrandom.sample(self.seq, 5):
self.assertTrue(elementinself.seq)

if__name__=='__main__':
unittest.main()