Dear buddies, I now have problem with this paragraph quoted from perldoc Devel::Peek:
The "quality" of a hash is defined as the total number of comparisons needed to access every element once, relative to the expected number needed for a random hash. The value can go over 100%.
The total number of comparisons is equal to the sum of the squares of the number of entries in each bucket. For a random hash of "<n"> keys into "<k"> buckets, the expected value is: n + n(n-1)/2k
My doubt is :

why “The total number of comparisons is equal to the sum of the squares of the number of entries in each bucket”holds in the first place?

Intuitively , I think "the total number of comparisons for a random hash of n keys into k buckets " should be n(n+k)/2k

In reply to About the expected number of comparisons for n keys into k buckets by PerlOnTheWay

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