Counting the number of inversions added. #133
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pydsa/count_inversions.py
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| merged , ans=_merge(L,R) | ||
| return merged , left+right+ans | ||
| return a , 0 | ||
| def count_inversions(a): |
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Please use 4 spaces for indentation, and follow PEP8
pydsa/tests/test_count_inversions.py
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| @@ -0,0 +1,4 @@ | |||
| from pydsa import count_inversions | |||
| def test_count_inversions(): | |||
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Leave 2 lines before defining function
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@CuriousLearner please review now. Apologies for the poor formatting initially. |
pydsa/count_inversions.py
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| Counts the number of inversions in an array. | ||
| Divide and conquer algorithm is used for same. | ||
| >>> from pydsa import count_inversions | ||
| >>> a = [1,20,6,4,5] |
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@aktech the function there returns a sorted array while here it's supposed to return a count.
pydsa/count_inversions.py
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| # Complexity : O(nlog(n)) | ||
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| def _merge(L, R): |
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This function is already present here : https://github.com/pydsa/pydsa/blob/master/pydsa/merge_sort.py#L5
| return m, cnt | ||
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| def merge_sort(a): |
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This one is also present here: https://github.com/pydsa/pydsa/blob/master/pydsa/merge_sort.py#L21
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@aktech The function there returns the sorted array and not the count of inversions.
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@aktech @CuriousLearner Could you please review? |
I added the counting inversions using merge sort algorithm. Please review.