Consider double hashing of the form \(h(k,i)=(h_1(k)+ih_2(k)) \text{mod m}\)…

2019

Consider double hashing of the form

\(h(k,i)=(h_1(k)+ih_2(k)) \text{mod m}\) where 

\(h_{1}(k) = \text{k mod m} \ , \ \ h_{2}(k)=1+(\text{k mod n})\) where \(n=m-1\) and \(m=701\) . For \(𝑘=123456\), what is the difference between first and second probes in terms of slots?

  1. A.

    255

  2. B.

    256

  3. C.

    257

  4. D.

    258

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Correct answer: C

Key calculations:

  • Given m = 701 and n = m - 1 = 700, and k = 123456.

  • Compute h1(k) = k mod m = 123456 mod 701 = 80.

  • Compute k mod n = 123456 mod 700 = 256.

  • Compute h2(k) = 1 + (k mod n) = 1 + 256 = 257.

  • Therefore the step (difference between the first and second probes) is h2 = 257 slots.

Answer: 257

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