Fixes #5774

merge_insertion_sort

Co-Authored-By: AilisOsswald 44617437+AilisOsswald@users.noreply.github.com

Describe your change:

We fixed the Issue of Merge-insertion-Sort not sorting correctly.

We have seen that there is already a PR but we would like to present our fix since it is a little bit different: reidstrieker@2ab90df

We have left all Code as it was before, except line 163
original:
if result[i] == collection[-i]:
corrected:
if result[i] == collection[-1]:

because as the flag name states we want to check if the current item in result is the last item of our input list. (which would be collection[-1] not [-i]

We think that both solutions should work, but the solution with checking (as described above) should perform a tiny bit better.
Normally we do this, since we know everything left to the current value is smaller than the value we will have to sort in:
result = result[: i + 1] + binary_search_insertion(result[i + 1 :], pivot)

If we find the last_odd_item in our result list, we know the same thing like above and we know that there is one additional value, which is already sorted - the last_odd_item. And with that knowlegde we can make the list we have to search through smaller and the list we don't have to look at larger by one each:
result = result[: i + 1 +1] + binary_search_insertion(result[i + 1 :], pivot)

Keeping this flag in the code should make it a bit quicker, since in some cases the list to be searched through is one element smaller.

Our next step would be writing more tests as suggested in this issue #5774. Should this be done in the same issue or in a new one?

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
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