d4d8397e5f
Adds some of the code I generated while studying for a role transfer at Google using the fantastic resource, InterviewCake.com. This work predates the mono-repo. I should think of ways to DRY up this code and the code in crack_the_coding_interview, but I'm afraid I'm creating unnecessary work for myself that way.
97 lines
2.6 KiB
Python
97 lines
2.6 KiB
Python
import unittest
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from collections import deque
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################################################################################
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# Solution
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################################################################################
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# get_path :: G(V, E) -> V -> V -> Maybe([V])
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def get_path(g, src, dst):
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q = deque()
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result = None
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seen = set()
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q.append(([], src))
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if src not in g or dst not in g:
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raise Exception
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while q:
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p, node = q.popleft()
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seen.add(node)
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if node == dst:
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if not result:
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result = p + [node]
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elif len(p + [node]) < len(result):
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result = p + [node]
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else:
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if node not in g:
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raise Exception
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for x in g.get(node):
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if not x in seen:
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q.append((p + [node], x))
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return result
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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 setUp(self):
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self.graph = {
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'a': ['b', 'c', 'd'],
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'b': ['a', 'd'],
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'c': ['a', 'e'],
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'd': ['a', 'b'],
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'e': ['c'],
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'f': ['g'],
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'g': ['f'],
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}
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def test_two_hop_path_1(self):
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actual = get_path(self.graph, 'a', 'e')
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expected = ['a', 'c', 'e']
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self.assertEqual(actual, expected)
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def test_two_hop_path_2(self):
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actual = get_path(self.graph, 'd', 'c')
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expected = ['d', 'a', 'c']
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self.assertEqual(actual, expected)
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def test_one_hop_path_1(self):
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actual = get_path(self.graph, 'a', 'c')
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expected = ['a', 'c']
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self.assertEqual(actual, expected)
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def test_one_hop_path_2(self):
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actual = get_path(self.graph, 'f', 'g')
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expected = ['f', 'g']
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self.assertEqual(actual, expected)
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def test_one_hop_path_3(self):
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actual = get_path(self.graph, 'g', 'f')
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expected = ['g', 'f']
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self.assertEqual(actual, expected)
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def test_zero_hop_path(self):
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actual = get_path(self.graph, 'a', 'a')
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expected = ['a']
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self.assertEqual(actual, expected)
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def test_no_path(self):
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actual = get_path(self.graph, 'a', 'f')
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expected = None
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self.assertEqual(actual, expected)
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def test_start_node_not_present(self):
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with self.assertRaises(Exception):
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get_path(self.graph, 'h', 'a')
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def test_end_node_not_present(self):
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with self.assertRaises(Exception):
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get_path(self.graph, 'a', 'h')
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unittest.main(verbosity=2)
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