Solve merging-ranges
Write a function to merge meeting times. Added an in-place solution, which the "Bonus" section suggested attempting to solve. - Added some simple benchmarks to test the performance differences between the in-place and not-in-place variants. To my surprise, the in-place solution was consistently slower than the not-in-place solution.
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scratch/deepmind/part_two/merging-ranges.py
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115
scratch/deepmind/part_two/merging-ranges.py
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import unittest
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import timeit
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# Solution that uses O(n) space to store the result.
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def not_in_place(xs):
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xs.sort()
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result = [xs[0]]
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for ca, cb in xs[1:]:
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pa, pb = result[-1]
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if ca <= pb:
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result[-1] = (pa, max(pb, cb))
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else:
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result.append((ca, cb))
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return result
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# Solution that uses O(1) space to store the result.
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def in_place(xs):
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xs.sort()
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i = 0
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j = i + 1
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while j < len(xs):
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pa, pb = xs[i]
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ca, cb = xs[j]
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if ca <= pb:
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xs[i] = (pa, max(pb, cb))
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del xs[j]
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else:
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i = j
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j += 1
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return xs
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def test_nip():
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inputs = [
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[(1, 3), (2, 4)],
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[(5, 6), (6, 8)],
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[(1, 8), (2, 5)],
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[(1, 3), (4, 8)],
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[(1, 4), (2, 5), (5, 8)],
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[(5, 8), (1, 4), (6, 8)],
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[(1, 10), (2, 5), (6, 8), (9, 10), (10, 12)],
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[(0, 1), (3, 5), (4, 8), (10, 12), (9, 10)],
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]
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for x in inputs:
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not_in_place(x)
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def test_ip():
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inputs = [
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[(1, 3), (2, 4)],
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[(5, 6), (6, 8)],
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[(1, 8), (2, 5)],
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[(1, 3), (4, 8)],
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[(1, 4), (2, 5), (5, 8)],
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[(5, 8), (1, 4), (6, 8)],
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[(1, 10), (2, 5), (6, 8), (9, 10), (10, 12)],
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[(0, 1), (3, 5), (4, 8), (10, 12), (9, 10)],
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]
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for x in inputs:
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in_place(x)
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merge_ranges = in_place
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setup = 'from __main__ import test_nip, test_ip'
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print(timeit.timeit('test_nip()', number=10000, setup=setup))
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print(timeit.timeit('test_ip()', number=10000, setup=setup))
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# Tests
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class Test(unittest.TestCase):
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def test_meetings_overlap(self):
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actual = merge_ranges([(1, 3), (2, 4)])
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expected = [(1, 4)]
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self.assertEqual(actual, expected)
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def test_meetings_touch(self):
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actual = merge_ranges([(5, 6), (6, 8)])
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expected = [(5, 8)]
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self.assertEqual(actual, expected)
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def test_meeting_contains_other_meeting(self):
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actual = merge_ranges([(1, 8), (2, 5)])
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expected = [(1, 8)]
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self.assertEqual(actual, expected)
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def test_meetings_stay_separate(self):
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actual = merge_ranges([(1, 3), (4, 8)])
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expected = [(1, 3), (4, 8)]
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self.assertEqual(actual, expected)
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def test_multiple_merged_meetings(self):
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actual = merge_ranges([(1, 4), (2, 5), (5, 8)])
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expected = [(1, 8)]
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self.assertEqual(actual, expected)
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def test_meetings_not_sorted(self):
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actual = merge_ranges([(5, 8), (1, 4), (6, 8)])
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expected = [(1, 4), (5, 8)]
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self.assertEqual(actual, expected)
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def test_one_long_meeting_contains_smaller_meetings(self):
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actual = merge_ranges([(1, 10), (2, 5), (6, 8), (9, 10), (10, 12)])
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expected = [(1, 12)]
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self.assertEqual(actual, expected)
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def test_sample_input(self):
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actual = merge_ranges([(0, 1), (3, 5), (4, 8), (10, 12), (9, 10)])
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expected = [(0, 1), (3, 8), (9, 12)]
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self.assertEqual(actual, expected)
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unittest.main(verbosity=2)
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@ -1,5 +1,5 @@
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* Array and string manipulation
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** TODO Merging Meeting Times
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** DONE Merging Meeting Times
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** DONE Reverse String in Place
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** TODO Reverse Words
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** TODO Merge Sorted Arrays
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