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Wednesday, January 29, 2014

Code puzzler: Tape Equilibrium

Suppose you get an array of ints of arbitrary length. Now we need to find out what is the mimimal absolute difference of the 2 sums of numbers if you split the array at any position in a left and right array. And preferably in a efficient way.


  1. It has reminded me of the in-place version of quicksort algorithm: http://en.wikipedia.org/wiki/Quicksort#In-place_version

    BTW, a couple of improvements to your implementation:
    1. You should avoid using Arrays.copyOfRange. It's so inefficient.
    2. You can immediately break the loop as soon as the following becomes true: (difference > minDifference).

  2. Well, my second point is incorrect if there may be negative ints.

  3. Yeah.... arrays are a pain to work with... I probably should convert the int array to a List first but even that takes a few lines of code extra... java does not autobox them unfortunately. But with a list I can easily take subLists.

  4. Hi, Thanks for this great image that explores and helps me to understand what the Tape-Equilibrium is!.