Which of the following is true about deleting a key-value pair from a hash table that uses separate chaining to resolve collisions?

Question

BlackTom AI · Accepted Answer

The question asks about deleting a key-value pair from a hash table that uses separate chaining for collision resolution. 
Option A: 'Deleting from the hash table can be done with simple linked-list node deletion, and no rehashing is required.' In a separate chaining scheme, each bucket contains a linked list of entries. To delete a specific key, you locate the appropriate bucket and remove the node from its linked list by updating pointers. Since removal of a node does not affect the distribution of other keys across buckets, rehashing is not needed. This statement aligns with the standard operation for deletions in separate chaining. 
Option B: 'After deletion, only the keys after the given node must be rehashed.' Rehashing would imply recomputing bucket indices for keys, which is unnecessary in separate chaining because each key’s bucket is determined by its own hash value, not by adjacency in the list. Deleting a node does not require rehashing the remaining nodes. This makes B misleading. 
Option C: 'After deletion, all keys must be rehashed.' This claims a global rehashing is required after any deletion, which is false for separate chaining; rehashing is typically thought of in the context of resizing the table or redistributing after a load factor change, not simply deleting a node. 
Option D: 'Deleting can take O(N^2)-time in the worst case when there are N elements in the hash table.' In separate chaining, deletion in a bucket is proportional to the length of that bucket’s list; the worst-case time for a single deletion is O(k) where k is the number of elements in that bucket, which in the worst case is O(N) if all elements collide into one bucket. However, O(N^2) would imply repeated linear-factor operations within a loop, which is not the standard characterization of a single delete operation. This makes D inaccurate for describing the typical deletion cost. 
Overall, the reasoning for each option emphasizes the mechanics of linked-list deletion within a bucket and clarifies why rehashing is not required, while also correcting common misconceptions about rehashing and time complexity in this context.

Which of the following is true about deleting a key-value pair from a hash table that uses separate chaining to resolve collisions?单项选择题

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Consider the hash table of size 11 that uses linear probing shown below, where the hash function is h(k) = (k mod 11). Thus h(14)=3, h(25)=3. What indices are examined if we now perform get(4)?

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Which is TRUE?

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Which of the following is true about deleting a key-value pair from a hash table that uses separate chaining to resolve collisions?单项选择题

类似问题

Open Addressing One of the advantages of chained hash table over the open addressing scheme is ______

Open Addressing One of the advantages of chained hash table over the open addressing scheme is ______

What is the worst-case complexity of get in separate chaining? (Make no assumption about the load factor or how good the hash function is.)

What is the worst-case complexity of insert in separate chaining? (Make no assumption about the load factor or how good the hash function is.)

In a separate chaining hashtable, what is the impact of increasing the load factor above 1?

Consider the hash table of size 11 that uses linear probing shown below, where the hash function is h(k) = (k mod 11). Thus h(14)=3, h(25)=3. What indices are examined if we now perform get(4)?

Consider an implementation of a hash table with linear probing where the hash function runs in constant time and the cost of comparison is also constant. What is the best-case time complexity of the __getitem__ method? Consider n is the number of items in the hash table.

Which is TRUE?

更多留学生实用工具

希望你的学习变得更简单

Consider an implementation of a hash table with linear probing where the hash function runs in constant time and the cost of comparison is also constant. What is the best-case time complexity of the getitem method? Consider n is the number of items in the hash table.