Solution to Odd-Occurrences-In-Array by codility

18 Sep

Question: https://codility.com/programmers/task/odd_occurrences_in_array

Question Name: Odd-Occurrences-In-Array or OddOccurrencesInArray

This question is completely the same as the Perm-Missing-Elem by codility. The comment from Kim is very helpful.

64 Replies to “Solution to Odd-Occurrences-In-Array by codility

  1. JavaScript solution
    Why I am getting only 11% for correctness?

  2. My Java solution (100%)

      • Right after “i = j – 1”, it goes into for loop and run “i++”. Eventually, for the next iteration, i = j. And we are accessing the first next character that is not A[old i].

    • Yes. It’s O(N).

      Thank you for your code.
      I just wrote O(NlogN) Code. It can’t solved.

  3. I’m quite new to programming but here’s my python solution. I didn’t realise I could have used XOR.

  4. Mi Javascript Solution 100%

  5. My very simple Java solution (100%).

  6. This is my solution in python
    I got a 100% score

  7. Does anyone know what the ^= means? The Perm-Missing-Elem by codility post that keeps being references does not explain this.

  8. In PHP 100% To All 😀

  9. I see lots of solutions that call sort but the standard sorts are comparison sorts and have run time O(N logN). The question asks for O(N). That they pass the test indicates that the system is unable to distinguish O(N) and O(N log N) but I don’t believe they are correct per the instructions.

  10. I have the following solution:

    but have only Correctness 80% because of the error during check:

    And this errors occurs everytime…
    Can somebody explain what is the issue in my solution?
    Thanks in advance!

  11. Another in Python, using set:

    • this is a perfect solution!!!
      But it still gave me this:
      Detected time complexity:
      O(N) or O(N*log(N))

      I’m new to python and returned to coding after a long time! what does this mean?

  12. Hallo. This is my C++ version. I am not sure, I get 100% but I am wondering if it is 100% bug-proof. I modify the python version of @Ty.

    And yes this is O(N logN) . I am wondering if is it possible to obtain something similar to the one of @Ivan Padron .

    • >> catch (exception& e) // I am not sure of this part
      It’s used to catch the odd occurrence, when the largest number occurs for odd number of times.

    • Thanks for your suggestion. Here is what I wrote on PHP and it gets 100% with Time complexity is O(N) or O(N*log(N)).

  13. Python 3.6

  14. Here’s the thing about all the solutions that sort and then iterate through the array. Sorting takes O(nlogn), so even if you are able to iterate through the array a single time to determine the odd occurrence, you will not meet the specified time complexity requirement.

  15. Hi, here are my 100 solution.

    https://app.codility.com/demo/results/trainingTJGJWC-323/

  16. Possible C++ solution:

  17. here is my 100% test pass but fails in time complexity

  18. This is my solution in C++ I got 100%

  19. I hijacked yours for solution in VB since nobody apparently uses it anymore except me. It got 100% so I guess it’s correct. I’m looking to learn Python soon after testing.

  20. 100% with O(N) or O(NlogN)

  21. i don’t know why my solution just get 77%
    time complexity is O(n**2)

    • I do not know your programming language, and did not debug the code. The idea is correct while inefficient. Also with some optimization, I guess ar is unnecessary.

  22. My 100% java solution:

    O(N) or O(N*log(N)) complexity

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