Wrote grouped_anagrams method. #1

dev-elle-up · 2019-09-15T04:45:55Z

Hash Table Practice

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Comprehension Questions

Question	Answer
Why is a good Hash Function Important?	Having a good hash function makes this data structure fast - O(1), ideally.
How can you judge if a hash function is good or not?	A good hash functions will: disburse items broadly across the internal array (to have a low density), reducing collisions; make it look like it's random; give very different indices for similar keys; be fast; be consistent.
Is there a perfect hash function? If so what is it?	No, there is not.
Describe a strategy to handle collisions in a hash table	One strategy to handle collisions in linear probing. When a collision happens, the hash function checks the next index in the internal array (bucket) until it finds an empty space.
Describe a situation where a hash table wouldn't be as useful as a binary search tree	Hash tables do not keep track of an order for the items they store. Therefore, a binary search tree is a better solution for any situation in which order matters.
What is one thing that is more clear to you on hash tables now	Hashes are using a function to convert a key to an index in an array where the value is stored. This is used both to store and to retrieve the value. Who knew?? So cool. 😎 Knowing this makes it all make sense and helped me connect all the dots.

…sts to match changes from Matt.

…icated about Big-O notation and the most efficient solution.

CheezItMan

Nice work, you hit the learning goal of this exercise. Well done.

CheezItMan · 2019-09-17T02:19:20Z

test/exercises.test.js


      // Assert
      expect(answer.sort()).to.eql([1]);
    });
  });

  describe.skip("valid sudoku", function() {
+    it("is not valid if a row has duplicate values", function() {


I'll add this to my set of tests

CheezItMan · 2019-09-17T02:23:17Z

lib/exercises.js

-function grouped_anagrams(strings) {
-  throw new Error("Method hasn't been implemented yet!");
+// Time Complexity: O(n) where n is the length of the array passed in as the argument "strings" because each item in the array is visited once
+// Space Complexity: O(1) (***Chris, is this right? It takes 2 times the space of 'strings' which reduces to 1. Or is it O(n) because the space taken is is 2 x n where n is the length of the 'strings' array?***)


I would say O(n) because you are building a JavaScript object which scales based on the size of the array.

CheezItMan · 2019-09-17T02:23:42Z

lib/exercises.js

+
+  strings.forEach(str => {
+    let tempStr = str.split('').sort().join(''); // alphabetize str
+    anagrams[tempStr] ? anagrams[tempStr].push(str) : anagrams[tempStr] = [str];


Good use of a ternary.

dev-elle-up added 4 commits September 14, 2019 21:25

Wrote grouped_anagrams method.

021a256

Added time and space complexity notes for anagrams method. Updated te…

ffd2d27

…sts to match changes from Matt.

Changed snake case to camel case for JS convention.

f563ff9

QUESTIONS IN THIS COMMIT. Wrote pseudocode for k_top_elements. Pontif…

b6e3d22

…icated about Big-O notation and the most efficient solution.

CheezItMan reviewed Sep 17, 2019

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Wrote grouped_anagrams method. #1

Wrote grouped_anagrams method. #1

dev-elle-up commented Sep 15, 2019

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CheezItMan Sep 17, 2019

CheezItMan Sep 17, 2019

CheezItMan Sep 17, 2019

Wrote grouped_anagrams method. #1

Are you sure you want to change the base?

Wrote grouped_anagrams method. #1

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dev-elle-up commented Sep 15, 2019

Hash Table Practice

Comprehension Questions

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