Open
Conversation
CheezItMan
reviewed
Nov 14, 2019
CheezItMan
left a comment
CheezItMan
left a comment
There was a problem hiding this comment.
Overall nice work, you hit the learning goals here. Well done. Check my comments below especially with regard to time/space complexity. Let me know if you have questions.
| if s.length <= 1 | ||
| return s | ||
| else | ||
| return s[-1] + reverse(s[1...-1]) + s[0] |
There was a problem hiding this comment.
s[1..-1] creates a new array and copies all the individual elements over and so is O(n) by itself.
| # Space complexity: ? | ||
| # Time complexity: O(n) | ||
| # Space complexity: O(n) | ||
| def reverse(s) |
There was a problem hiding this comment.
👍
This works, but because you create a new array with each recursive call this is O(n2) for both time/space complexity.
| # Space complexity: ? | ||
| # Time complexity: O(???) | ||
| # Space complexity: O(???) | ||
| def reverse_inplace(s) |
lib/recursive-methods.rb
Outdated
Comment on lines
117
to
118
| # Time complexity: O(n) | ||
| # Space complexity: O(1) |
There was a problem hiding this comment.
- You are doing recursion so the system stack applies to the space complexity (at least O(n))
- Since you are doing
array.shiftthis is by itself an O(n) time operation. Combined with the recursion it's O(n2)
| # Space complexity: ? | ||
| # Time complexity: O(n) | ||
| # Space complexity: O(1) | ||
| def is_palindrome(s) |
There was a problem hiding this comment.
👍 This works, but you have similar time/space issues with the above methods.
| # Space complexity: ? | ||
| # Time complexity: O(n), where n is the longer number | ||
| # Space complexity: O(n) | ||
| def digit_match(n, m) |
lib/recursive-methods.rb
Outdated
|
|
||
|
|
||
| # Added Fun | ||
| # Time complexity: O(n*2^n), almost I think. |
There was a problem hiding this comment.
O(2n), actually
Space complexity O(n)
| # Time complexity: O(n*2^n), almost I think. | ||
| # It'll go n-1 levels deep, with up to 2^n leaves, so n*2^n... | ||
| # Space complexity: O(n*2^n)...? not sure | ||
| def fib(n) |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Yeah... IDK if I'm allowed to solve reverse_inplace the way I did...