Leaves - Mariya #38

M-Burr · 2020-03-12T21:18:39Z

Hash Table Practice

Congratulations! You're submitting your assignment!

Question	Answer
Why is a good Hash Function Important?	It enables faster look-up times and reduces collusions
How can you judge if a hash function is good or not?	It should map different keys to different values & indexing should appear random. A good hash function should also be fast.
Is there a perfect hash function? If so what is it?	There is no perfect hash function.
Describe a strategy to handle collisions in a hash table	chaining with linked list
Describe a situation where a hash table wouldn't be as useful as a binary search tree	when elements need to be sorted
What is one thing that is more clear to you on hash tables now	how collusions are prevented

CheezItMan

You hit the main learning goals here. Take a look at my inline comments and let me know what questions you have. Well done.

CheezItMan · 2020-03-18T17:09:52Z

lib/exercises.rb

+# Time Complexity: O(n)
+# Space Complexity: O(n)

 def grouped_anagrams(strings)


👍 This works and assuming the words are small you are right on the time/space complexity.

CheezItMan · 2020-03-18T17:10:33Z

lib/exercises.rb

+    end
+  end 
+
+  values_sort =  counter_hash.sort_by {|key, value| -value}


This sort depends on the number of distinct elements, so it's worst-case O(n log n)

CheezItMan · 2020-03-18T17:12:27Z

lib/exercises.rb

+# Time Complexity: O(n)
+# Space Complexity: O(n)
 def top_k_frequent_elements(list, k)


This works, but take a look at my comments on big O.

CheezItMan and others added 2 commits September 11, 2019 13:24

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CheezItMan reviewed Mar 18, 2020

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