019f8fd211
git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
66 lines
1.8 KiB
Python
66 lines
1.8 KiB
Python
import unittest
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################################################################################
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# Solution
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################################################################################
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class QueueTwoStacks(object):
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def __init__(self):
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self.a = []
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self.b = []
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def enqueue(self, x):
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self.a.append(x)
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def dequeue(self):
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if self.b:
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return self.b.pop()
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else:
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while self.a:
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self.b.append(self.a.pop())
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return self.dequeue()
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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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def test_basic_queue_operations(self):
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queue = QueueTwoStacks()
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queue.enqueue(1)
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queue.enqueue(2)
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queue.enqueue(3)
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actual = queue.dequeue()
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expected = 1
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self.assertEqual(actual, expected)
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actual = queue.dequeue()
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expected = 2
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self.assertEqual(actual, expected)
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queue.enqueue(4)
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actual = queue.dequeue()
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expected = 3
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self.assertEqual(actual, expected)
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actual = queue.dequeue()
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expected = 4
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self.assertEqual(actual, expected)
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def test_error_when_dequeue_from_new_queue(self):
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queue = QueueTwoStacks()
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with self.assertRaises(Exception):
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queue.dequeue()
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def test_error_when_dequeue_from_empty_queue(self):
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queue = QueueTwoStacks()
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queue.enqueue(1)
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queue.enqueue(2)
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actual = queue.dequeue()
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expected = 1
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self.assertEqual(actual, expected)
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actual = queue.dequeue()
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expected = 2
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self.assertEqual(actual, expected)
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with self.assertRaises(Exception):
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queue.dequeue()
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unittest.main(verbosity=2)
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