Ports - Kasey #20
Ports - Kasey #20
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ace-n
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ace-n
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Tests pass and existing complexity analysis LGTM other than variable definitions. 👍
However, I feel like we can probably improve our space complexity (which is what we want, per the README) - even if time complexity suffers as a result. Any ideas on how we'd do that?
| # Returns a new array to that contains elements in the intersection of the two input arrays | ||
| # Time complexity: ? | ||
| # Space complexity: ? | ||
| # Time complexity: Time complexity is O(n) (or, O(n+m)) we are looping through one array O(n), then searching worst case for a look up a hash table O(n) |
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I suspect this is correct - but what is m here? 🙂
(Make sure to define all the letters you use.)
| # Time complexity: ? | ||
| # Space complexity: ? | ||
| # Time complexity: Time complexity is O(n) (or, O(n+m)) we are looping through one array O(n), then searching worst case for a look up a hash table O(n) | ||
| # Space complexity: O(n) with n elements in the hash table. |
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I take it n in the time and space complexities are the same? (It never hurts to be explicit when discussing complexity.)
| end | ||
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| def sorting(longer, shorter) | ||
| holder_hash = Hash.new |
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holder_hash and intersec are extra datastructures that increase space complexity. Can you think of a better approach that doesn't use extra datastructures and has a space complexity of O(1)? (Hint: it may have worse time complexity than your current one.)
| holder_hash = Hash.new | ||
| longer.each do |num| | ||
| holder_hash[num] = 1 | ||
| #it won't work of I just do holder_hash = Hash.new, should set default value to nil, but it errors on the tests, why? |
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Because you have to tell holder_hash what values are in longer. Otherwise, when you loop through shorter holder_hash won't contain anything, and this method will return an empty array.
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