019f8fd211
git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
82 lines
2.2 KiB
Python
82 lines
2.2 KiB
Python
import unittest
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################################################################################
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# Solution
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################################################################################
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def length(x):
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if not x:
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return 0
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else:
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count = 1
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while x:
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x = x.next
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count += 1
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return count
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def kth_to_last_node(k, x):
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hops = length(x) - 1
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dest = hops - k
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if k == 0:
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raise Exception("Our God doesn't support this kind of behavior.")
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if dest < 0:
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raise Exception('Value k to high for list.')
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while dest > 0:
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x = x.next
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dest -= 1
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return x
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################################################################################
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# Tests
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################################################################################
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class Test(unittest.TestCase):
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class LinkedListNode(object):
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def __init__(self, value, next=None):
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self.value = value
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self.next = next
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def get_values(self):
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node = self
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values = []
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while node is not None:
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values.append(node.value)
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node = node.next
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return values
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def setUp(self):
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self.fourth = Test.LinkedListNode(4)
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self.third = Test.LinkedListNode(3, self.fourth)
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self.second = Test.LinkedListNode(2, self.third)
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self.first = Test.LinkedListNode(1, self.second)
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def test_first_to_last_node(self):
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actual = kth_to_last_node(1, self.first)
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expected = self.fourth
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self.assertEqual(actual, expected)
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def test_second_to_last_node(self):
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actual = kth_to_last_node(2, self.first)
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expected = self.third
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self.assertEqual(actual, expected)
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def test_first_node(self):
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actual = kth_to_last_node(4, self.first)
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expected = self.first
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self.assertEqual(actual, expected)
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def test_k_greater_than_linked_list_length(self):
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with self.assertRaises(Exception):
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kth_to_last_node(5, self.first)
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def test_k_is_zero(self):
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with self.assertRaises(Exception):
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kth_to_last_node(0, self.first)
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unittest.main(verbosity=2)
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