Hashing: Quadratic Probing sequence

AI Thread Summary
The discussion centers on generating a probing sequence using the quadratic probing technique with specific values: j = 4, table size = 19, and h(K) = 9. The user attempts to calculate the probing sequence but encounters an error with the calculation of h(k) - 4^2, which results in -7 instead of the expected 12. Guidance is sought on how to correctly derive the probing sequence, and suggestions are made to clarify notation and reference additional resources. The conversation highlights the importance of accurate calculations in hashing algorithms.
zak100
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Homework Statement



Hi,
I want to generate probing sequence using quadratinc probing technique. If j =4 & table size = 19 & assuming h(K) = 9.

Homework Equations


h(K), h(K) + 1, h(k) -1, h(k) + 4, h(K) - 4, ... h(K) + (TSIZE -1)power 2 / 4, h(k) - (TSIZE -1) power 2 /4 all divided modulo TSize.

The Attempt at a Solution


The book shows following sequence:
9, 10, 8, 13, 5, 18, 0, 6, 12, 15, 3, 7, 11, 1, 17, 16, 2, 14, 4

I am able to find:
h(k) = 9%19 = 9
h(k) + 1 power 2 = 10 % 19 = 10
h(k) - 1 power 2 = 8 % 19 = 8
h(k) + 2 power 2 = 13 % 19 = 13
h(k) - 2 power 2 = 5 % 19 = 5
h(k) + 3 power 2 = 18 % 19 = 18
h(k) - 3 power 2 = 0
h(k) + 4 power 2 = 9 + 16 = 25 % 19 = 6
h(k) - 4 power 2 = 9 -16 = -7 %19 = -7 9 which is wrong,

Some body please guide me how to solve it.

Zulfi.
 
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I am editing this part. I can't find the edit option

The Attempt at a Solution


The book shows following sequence:
9, 10, 8, 13, 5, 18, 0, 6, 12, 15, 3, 7, 11, 1, 17, 16, 2, 14, 4

I am able to find:
h(k) = 9%19 = 9
h(k) + 1 power 2 = 10 % 19 = 10
h(k) - 1 power 2 = 8 % 19 = 8
h(k) + 2 power 2 = 13 % 19 = 13
h(k) - 2 power 2 = 5 % 19 = 5
h(k) + 3 power 2 = 18 % 19 = 18
h(k) - 3 power 2 = 0
h(k) + 4 power 2 = 9 + 16 = 25 % 19 = 6
h(k) - 4 power 2 = 9 -16 = -7 %19 = -7 which is wrong, it should be 12. I know 19 -7 = 12. But i don't know how to get it.

Some body please guide me how to solve it.

Zulfi.[/QUOTE]
 
zak100 said:
I am editing this part. I can't find the edit option

The Attempt at a Solution


The book shows following sequence:
9, 10, 8, 13, 5, 18, 0, 6, 12, 15, 3, 7, 11, 1, 17, 16, 2, 14, 4

I am able to find:
h(k) = 9%19 = 9
h(k) + 1 power 2 = 10 % 19 = 10
h(k) - 1 power 2 = 8 % 19 = 8
h(k) + 2 power 2 = 13 % 19 = 13
h(k) - 2 power 2 = 5 % 19 = 5
h(k) + 3 power 2 = 18 % 19 = 18
h(k) - 3 power 2 = 0
h(k) + 4 power 2 = 9 + 16 = 25 % 19 = 6
h(k) - 4 power 2 = 9 -16 = -7 %19 = -7 which is wrong, it should be 12. I know 19 -7 = 12. But i don't know how to get it.

Some body please guide me how to solve it.

Zulfi.
Have you seen this wikipedia article? https://en.wikipedia.org/wiki/Quadratic_probing
What is the complete problem statement? Are the numbers in your list the values in the hash table, or are they the things for which hash values need to be found?

Also, instead of writing "h(k) + 2 power 2" and so on, at the very least write this as h(k) + 2^2.

Even better, use LaTeX to write ##h(k) + 2^2##. My script for this is ##h(k) + 2^2##.
 

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