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## Double Hashing Multiple choice Questions and Answers (MCQs)

Question 1 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

Double hashing is one of the best methods available for open addressing.

True | |

False |

Question 1 Explanation:

Double hashing is one of the best methods for open addressing because the permutations produced have many characteristics of randomly chosen permutations.

Question 2 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

What is the hash function used in Double Hashing?

(h1(k) - i*h2(k))mod m | |

h1(k) + h2(k) | |

(h1(k) + i*h2(k))mod m | |

(h1(k) + h2(k))mod m |

Question 2 Explanation:

Double hashing uses a hash function of the form (h1(k) + i*h2(k))mod m where h1 and h2 are auxiliary hash functions and m is the size of the hash table.

Question 3 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

On what value does the probe sequence depend on?

c1 | |

k | |

c2 | |

m |

Question 3 Explanation:

The probe sequence depends in upon the key k since the initial probe position, the offset or both may vary.

Question 4 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

The value of h2(k) can be composite relatively to the hash table size m.

True | |

False |

Question 4 Explanation:

The value h2(k) must be relatively prime to the hash table size m for the entire hash table to be searched. It can be ensured by having m in powers of 2 and designing h2 so that it produces an odd number.

Question 5 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER] |

What are the values of h1(k) and h2(k) in the hash function?

h1(k) = m mod k h2(k) = 1+ (m' mod k) | |

h1(k) = 1 + (m mod k) h2(k) = m' mod k | |

h1(k) = 1+ (k mod m) h2(k) = k mod m | |

h1(k) = k mod m h2(k) = 1+ (k mod m') |

Question 5 Explanation:

The values h1(k) and h2(k) are k mod m and 1+(k mod m') respectively where m is a prime number and m' is chosen slightly less than m. (m'=m-1).

There are 5 questions to complete.