91811236a5
Solves the InterviewCake.com problem that asks us to write a function that returns the number, y, that occurs twice in a list, xs, where xs is an unsorted list of integers from 1..n with a length of n + 1.
29 lines
656 B
Python
29 lines
656 B
Python
import unittest
|
|
|
|
|
|
def find_repeat(xs):
|
|
n = max(xs)
|
|
expected_sum = (n + 1) * n / 2
|
|
actual_sum = sum(xs)
|
|
return actual_sum - expected_sum
|
|
|
|
|
|
# Tests
|
|
class Test(unittest.TestCase):
|
|
def test_short_list(self):
|
|
actual = find_repeat([1, 2, 1])
|
|
expected = 1
|
|
self.assertEqual(actual, expected)
|
|
|
|
def test_medium_list(self):
|
|
actual = find_repeat([4, 1, 3, 4, 2])
|
|
expected = 4
|
|
self.assertEqual(actual, expected)
|
|
|
|
def test_long_list(self):
|
|
actual = find_repeat([1, 5, 9, 7, 2, 6, 3, 8, 2, 4])
|
|
expected = 2
|
|
self.assertEqual(actual, expected)
|
|
|
|
|
|
unittest.main(verbosity=2)
|