Jessica

[jessicacaley]

Hash Table Practice

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Comprehension Questions

Question	Answer
Why is a good Hash Function Important?	It allows an even distribution within the hash and helps avoid collisions, which keeps lookup at constant time instead of O(n).
How can you judge if a hash function is good or not?	The hash is evenly distributed and seems random.
Is there a perfect hash function? If so what is it?	No.
Describe a strategy to handle collisions in a hash table	One strategy is to make a linked list of the collision key/value pairs at the collision location.
Describe a situation where a hash table wouldn't be as useful as a binary search tree	If a traversal would be helpful for any reason.
What is one thing that is more clear to you on hash tables now	I feel more clear about how lookup works when collisions occur (it helped to understand that the worst case is actually O(n) for any (poorly implemented) solution, just like going through an array).

[CheezItMan]

Nice work, your Sudoku method could use a bit of drying up, but it all works. You even did the kth common elements as well. Nice work.

Take a look at my comments and let me know what questions you have.

[CheezItMan]

I would say that it's O(n) where n is the number of strings if the length of any particular string is pretty small.

It's O(n m log m) where n is the number of strings and m is the average length of any particular string, if the strings can be arbitrarily large.

[CheezItMan]

👍

[CheezItMan]

This looks pretty repetitive, could you instead create a method to do this on different subgrids?