fix sort/radix_sort (#395)

[InnoFang]

(Put an X inside the [ ] to denote check mark [X].)

• If creating a new file :

  • added links to it in the README files ?
  • included tests with it ?
  • added description (overview of algorithm, time and space compleixty, and possible edge case) in docstrings ?

• if done some changes :

  • wrote short description in the PR explaining what the changes do ?
    Use position as a loop variable instead of is_done to fix the bug that isn't to be find easily.
  • Fixes #[issue number] if related to any issue
    bug report for radix sort #395

• other

[coveralls]

Pull Request Test Coverage Report for Build 736

• 2 of 4 (50.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 71.49%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
algorithms/sort/radix_sort.py	2	4	50.0%

Totals
Change from base Build 729:	0.01%
Covered Lines:	4303
Relevant Lines:	6019

---

💛 - Coveralls

[keon]

Thanks very much! I added one minor comment.

[keon]

Nit: could you add a new line at the end?

[InnoFang]

OK