Python/dynamic_programming/coin_change.py
Himadri Ganguly 46af42d47a
Fix coin change (#2571)
* Removed unused variable m.

* Doctests are modified to match functions.

* Added condition for negative values.

* Fixed white-space around operator.

* Fixed W293 blank line contains white-space error.

* Update dynamic_programming/coin_change.py

Co-authored-by: Tapajyoti Bose <44058757+ruppysuppy@users.noreply.github.com>

* Fixed error in code.

* Fixed whited spacing.

* Fixed PEP8 error.

* Added more test cases for coin change problem.

* Removed extra test for negetive value.

Co-authored-by: Tapajyoti Bose <44058757+ruppysuppy@users.noreply.github.com>
2020-10-24 00:55:13 +08:00

47 lines
1.1 KiB
Python

"""
You have m types of coins available in infinite quantities
where the value of each coins is given in the array S=[S0,... Sm-1]
Can you determine number of ways of making change for n units using
the given types of coins?
https://www.hackerrank.com/challenges/coin-change/problem
"""
def dp_count(S, n):
"""
>>> dp_count([1, 2, 3], 4)
4
>>> dp_count([1, 2, 3], 7)
8
>>> dp_count([2, 5, 3, 6], 10)
5
>>> dp_count([10], 99)
0
>>> dp_count([4, 5, 6], 0)
1
>>> dp_count([1, 2, 3], -5)
0
"""
if n < 0:
return 0
# table[i] represents the number of ways to get to amount i
table = [0] * (n + 1)
# There is exactly 1 way to get to zero(You pick no coins).
table[0] = 1
# Pick all coins one by one and update table[] values
# after the index greater than or equal to the value of the
# picked coin
for coin_val in S:
for j in range(coin_val, n + 1):
table[j] += table[j - coin_val]
return table[n]
if __name__ == "__main__":
import doctest
doctest.testmod()