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@kdow kdow commented Sep 15, 2019

Hash Table Practice

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Comprehension Questions

Question Answer
Why is a good Hash Function Important? Good hash functions will provide constant lookup time, whereas bad hash functions can get up to linear lookup time.
How can you judge if a hash function is good or not? Constant lookup time, consistent but appears random, elements distributed uniformly across the collection.
Is there a perfect hash function? If so what is it? No
Describe a strategy to handle collisions in a hash table Chaining will make each bucket of the hash table's internal array the head of a linked list which subsequent element can be added on to.
Describe a situation where a hash table wouldn't be as useful as a binary search tree When the order of the elements is important.
What is one thing that is more clear to you on hash tables now Hash functions

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@CheezItMan CheezItMan left a comment

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Nice work, you did the requirements here, well done.

# Each subarray will have strings which are anagrams of each other
# Time Complexity: ?
# Space Complexity: ?
# Time Complexity: O(n)

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If the strings are small enough, yes.

grouped[word.chars.sort.join] += [i]
end

return grouped.map { |key, indices| indices.map { |i| strings[i] } }

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Why put the indexes into grouped instead of putting the words in the first place? Just seems a little odd.

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2 participants