blob: 55e0db573730a25e9cf591c8e8d20b7c0056cb5f (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
|
#!/usr/bin/env python3
# Challenge 068
#
# TASK #2 > Reorder List
# Submitted by: Mohammad S Anwar
# You are given a singly linked list $L as below:
#
# L0 ? L1 ? ... ? Ln-1 ? Ln
# Write a script to reorder list as below:
#
# L0 ? Ln ? L1 ? Ln-1 ? L2 ? Ln-2 ?
# You are ONLY allowed to do this in-place without altering the nodes' values.
#
# Example
# Input: 1 ? 2 ? 3 ? 4
# Output: 1 ? 4 ? 2 ? 3
import unittest
def reorder_list(l):
# get second element
tail = l[1]
# get and remove last element
p = tail
last = None
while len(p) > 1:
last = p
p = p[1]
eln = last.pop()
return [l[0], [eln[0], tail]]
class TestReorderList(unittest.TestCase):
def test_reorder_list(self):
self.assertEqual(reorder_list([1, [2, [3, [4]]]]), [1, [4, [2, [3]]]])
if __name__ == '__main__':
unittest.main()
|
