Question

I have a question about rehashing. Let us say, we have a hash table of size 7, and our hash function is (key%tableSize). We insert 24 to the table, and 24 will be at index 3 since 24%7=3. Then, let us say we added more elements, and now we want to rehash. The table size will be twice the size of the initial table, i.e. new table size will be 14. Then, while copying the elements to the new hash table, for example, while copying the element 24, will it still be in the index 3, or will it be at the index 24%14=10. I mean, do we use the new table size while copying the elements, or the elements stay in their initial indexes?
Thanks

Answer 1

It’s depend on your hashing function. In your case you should use key%size_of_table else slots after 7 will never be mapped by hashing function. These slots will occupied only when you chose linear probing in order to tackle the collision.(Where we look for next empty slot). Chosing new size will help to reduce the collisions at early stage, else it would be the case table haven’t reached the Load Factor still you are facing lot of collisions.