I'm basically looking for a good algorithm or method to do the following: I have 10 numbers, you can use List<Integer> or int[] or what ever you want.

I want to sort the 10 numbers so the sum of the first 5 is approximately (or exactly if possible) equal to the sum of the last 5. The sum of the first 5 must be as close as possible to the sum of the last 5.

saumil baxi, I don't think that will work. What if your set of numbers were

1,2,3,4,5,6,7,8,9,100

If i'm reading your algorithm correctly, you would sort them like:

group 1: 100, 8, 6, 4, 2: Sum is 120 group 2: 9, 7, 5, 3, 1: Sum is 25 diff = 95

But this would be a better way to do it:

group 1: 100, 1, 2, 3, 4: Sum = 110 group 2: 5,6,7,8,9: Sum = 35 diff = 75

I think your best bet is to go through the numbers from largest to smallest. Add each number to whichever group has the lowest sum. If the sums are the same, it doesn't matter.

I haven't proved to myself this is the correct way to go, but it feels right to me...

There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors

Sam Benry
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Joined: Mar 21, 2008
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Interesting, I wrote this quickly, what do you think ?