about summary refs log tree commit diff
path: root/universe/data_structures_and_algorithms/coins.py
blob: eb5754f98210e814896ce4f7c3b6791e2d29e743 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
import unittest
from math import floor

################################################################################
# Solution
################################################################################

# change_possibilities :: Int -> [Int] -> Int
def change_possibilities(n, xs):
    combinations = [0] * (n + 1)
    combinations[0] = 1

    for x in xs:
        for i in range(len(combinations)):
            if i >= x:
                combinations[i] += combinations[i - x]

    return combinations[n]


################################################################################
# Tests
################################################################################
class Test(unittest.TestCase):

    def test_sample_input(self):
        actual = change_possibilities(4, (1, 2, 3))
        expected = 4
        self.assertEqual(actual, expected)

    def test_one_way_to_make_zero_cents(self):
        actual = change_possibilities(0, (1, 2))
        expected = 1
        self.assertEqual(actual, expected)

    def test_no_ways_if_no_coins(self):
        actual = change_possibilities(1, ())
        expected = 0
        self.assertEqual(actual, expected)

    def test_big_coin_value(self):
        actual = change_possibilities(5, (25, 50))
        expected = 0
        self.assertEqual(actual, expected)

    def test_big_target_amount(self):
        actual = change_possibilities(50, (5, 10))
        expected = 6
        self.assertEqual(actual, expected)

    def test_change_for_one_dollar(self):
        actual = change_possibilities(100, (1, 5, 10, 25, 50))
        expected = 292
        self.assertEqual(actual, expected)


unittest.main(verbosity=2)