Using the division method [h(k) = k mod m], at which positions are the key…
2021
Using the division method [h(k) = k mod m], at which positions are the key values 177 and 197 stored in a hash table when the size of the hash table is 57?
- A.
6, 26
- B.
7, 27
- C.
26, 6
- D.
27, 7
Attempted by 58 students.
Show answer & explanation
Correct answer: A
Concept
In the division method of hashing, a key k is mapped to a slot using the hash function h(k) = k mod m, where m is the table size. The remainder of k divided by m gives the home address, so every result lies in the range 0 to m − 1. The position depends only on the remainder, not on the quotient.
Application
Here m = 57. Compute the remainder of each key on division by 57:
177 = 57 × 3 + 6, so 177 mod 57 = 6. Key 177 goes to address 6.
197 = 57 × 3 + 26, so 197 mod 57 = 26. Key 197 goes to address 26.
Taking the keys in the stated order (177 first, then 197), the addresses are 6 and 26.
Cross-check
Both addresses satisfy 0 ≤ address ≤ 56, the valid index range for a table of size 57. Re-multiplying confirms the remainders: 57 × 3 + 6 = 177 and 57 × 3 + 26 = 197. So the keys 177 and 197 hash to 6 and 26.