# Pairwise question

I have been studying the Pairwise problem description and looked over the tests and expected results.

I must be missing something, but I can not understand how the following test is valid:

pairwise([0, 0, 0, 0, 1, 1], 1) should return 10

My thinking if I take the first zero (index = 0) and pair it with the 1st one (index 4), the sum should be 4. Even if I chose the 4th zero (index = 3) and pair it with the last zero (index 5), the sum would still only be 8.

Also, the problem description says â€śOnce an element has been used, it cannot be reused to pair with another.â€ť Does â€śusedâ€ť mean used in a pair or attempted to use in a pair?

Obviously, I am not understanding the problem description. Any insight would be great.

Thanks,
Randell

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So,
pairwise([0, 0, 0, 0, 1, 1], 1) should return 10.

What I think youâ€™re missing is that you can have more than one pair.

You take the first 0 and the first 1 --> `0+4=4`
You take the second 0 and the second 1 --> `1+5=6`
Then, `4+6=10`

You need to add all sums, and always use first the ones with lower index.

Actually, I saw the extra pair, but I was interpreting the following problem statement differently. I originally thought it meant when multiples of same elements existed, only use the pair which had the smallest sum. So, that is why I was thinking it should be four.

If multiple pairs are possible that have the same numeric elements but different indices, return the smallest sum of indices.

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