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# Hash Tables with Linear Probing MCQs

1 - Question

Which of the following problems occur due to linear probing? a) Primary collision b) Secondary collision c) Separate chaining d) Extendible hashing

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Answer: a
Explanation: Primary collision occurs due to linear probing technique. It is overcome using a quadratic probing technique.
2 - Question

How many probes are required on average for insertion and successful search? a) 4 and 10 b) 2 and 6 c) 2.5 and 1.5 d) 3.5 and 1.5

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Answer: c
Explanation: Using formula, the average number of probes required for insertion is 2.5 and for a successful search, it is 1.5.
3 - Question

What is the load factor for an open addressing technique? a) 1 b) 0.5 c) 1.5 d) 0

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Answer: b
Explanation: The load factor for an open addressing technique should be 0.5. For separate chaining technique, the load factor is 1.
4 - Question

Which of the following is not a collision resolution strategy for open addressing? a) Linear probing b) Quadratic probing c) Double hashing d) Rehashing

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Answer: d
Explanation: Linear probing, quadratic probing and double hashing are all collision resolution strategies for open addressing whereas rehashing is a different technique.
5 - Question

In linear probing, the cost of an unsuccessful search can be used to compute the average cost of a successful search. a) True b) Answer: a Explanation: Using random collision resolution algorithm, the cost of an unsuccessful search can be used to compute the average cost of a successful search.

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Answer: a
Explanation: Using random collision resolution algorithm, the cost of an unsuccessful search can be used to compute the average cost of a successful search.
6 - Question

Which of the following is the correct function definition for linear probing? a) F(i)= 1 b) F(i)=i c) F(i)=i2 d) F(i)=i+1

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Answer: b
Explanation: The function used in linear probing is defined as, F(i)=I where i=0,1,2,3….,n.
7 - Question

___________ is not a theoretical problem but actually occurs in real implementations of probing. a) Hashing b) Clustering c) Rehashing d) Collision

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Answer: b
Explanation: Clustering is not a theoretical problem but it occurs in implementations of hashing. Rehashing is a kind of hashing.
8 - Question

What is the hash function used in linear probing? a) H(x)= key mod table size b) H(x)= (key+ F(i2)) mod table size c) H(x)= (key+ F(i)) mod table size d) H(x)= X mod 17

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Answer: c
Explanation: The hash function used in linear probing is defined to be H(x)= (key+ F(i)) mod table size where i=0,1,2,3,…,n.
9 - Question

Hashing can be used in online spelling checkers. a) True b) False

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Answer: a
Explanation: If misspelling detection is important, an entire dictionary can be pre-hashed and words can be checked in constant time.
10 - Question

In the following given hash table, use linear probing to find the location of 49.

0 | |

1 | |

2 | |

3 | |

4 | |

5 | |

6 | |

7 | |

8 | 18 |

9 | 89 |

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Answer: d
Explanation: Initially, collision occurs while hashing 49 for the first time.
Hence, after setting f(i)=1, the hashed location is found to be 0.
11 - Question

What is the formula to find the expected number of probes for an unsuccessful search in linear probing? a) 121+1(1−⅄) b) 121+1(1−⅄)2 c) 121+1(1+⅄) d) 121+1(1+⅄)(1−⅄)