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author | Vincent Ambo <mail@tazj.in> | 2021-12-13T22·51+0300 |
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committer | Vincent Ambo <mail@tazj.in> | 2021-12-13T23·15+0300 |
commit | 019f8fd2113df4c5247c3969c60fd4f0e08f91f7 (patch) | |
tree | 76a857f61aa88f62a30e854651e8439db77fd0ea /users/wpcarro/scratch/data_structures_and_algorithms/find-duplicate-optimize-for-space.py | |
parent | 464bbcb15c09813172c79820bcf526bb10cf4208 (diff) | |
parent | 6123e976928ca3d8d93f0b2006b10b5f659eb74d (diff) |
subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226
git-subtree-dir: users/wpcarro git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208 git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f Change-Id: I6105b3762b79126b3488359c95978cadb3efa789
Diffstat (limited to 'users/wpcarro/scratch/data_structures_and_algorithms/find-duplicate-optimize-for-space.py')
-rw-r--r-- | users/wpcarro/scratch/data_structures_and_algorithms/find-duplicate-optimize-for-space.py | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/users/wpcarro/scratch/data_structures_and_algorithms/find-duplicate-optimize-for-space.py b/users/wpcarro/scratch/data_structures_and_algorithms/find-duplicate-optimize-for-space.py new file mode 100644 index 000000000000..e2739f0f6055 --- /dev/null +++ b/users/wpcarro/scratch/data_structures_and_algorithms/find-duplicate-optimize-for-space.py @@ -0,0 +1,61 @@ +from math import floor +import unittest + + +################################################################################ +# Solution +################################################################################ +def bounds(r): + ct = len(r) + if ct % 2 == 0: + h = int(ct / 2) + return ct, h + else: + h = floor(ct / 2) + return ct, h + + +def find_repeat(xs): + ct, h = bounds(xs) + rl = range(1, h + 1) + rr = range(h + 1, ct) + while True: + nl = len([None for x in xs if x in rl]) + nr = len([None for x in xs if x in rr]) + branch = rl if nl > nr else rr + if len(branch) == 1: + return branch[0] + ct, h = bounds(branch) + rl = range(branch[0], branch[0]) + rr = range(branch[0] + h, branch[-1] + 1) + raise Exception( + 'We could not find any duplicates in xs. Perhaps xs did not adhere to the usage contract.' + ) + + +################################################################################ +# Tests +################################################################################ +class Test(unittest.TestCase): + def test_just_the_repeated_number(self): + actual = find_repeat([1, 1]) + expected = 1 + self.assertEqual(actual, expected) + + def test_short_list(self): + actual = find_repeat([1, 2, 3, 2]) + expected = 2 + self.assertEqual(actual, expected) + + def test_medium_list(self): + actual = find_repeat([1, 2, 5, 5, 5, 5]) + expected = 5 + self.assertEqual(actual, expected) + + def test_long_list(self): + actual = find_repeat([4, 1, 4, 8, 3, 2, 7, 6, 5]) + expected = 4 + self.assertEqual(actual, expected) + + +unittest.main(verbosity=2) |