Julia Kingrey #26
Open
Julia Kingrey #26
Conversation
This file contains 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
CheezItMan
reviewed
Mar 18, 2020
Comment on lines
+2
to
+5
| # Time Complexity: n log n -- n to put elements in heap, log n to sort, | ||
| # and n log n put them back in the array | ||
| # Space Complexity: O(n) | ||
| def heapsort(list) |
Comment on lines
+18
to
21
| # Time Complexity: usually O(1) because unlike adding to the front, appending / | ||
| # adding to the end doesn't require reordering the whole array | ||
| # Space Complexity: O(1) | ||
| def add(key, value = key) |
There was a problem hiding this comment.
The time complexity is O(log n) because the heap_up method is O(log n). Because it's recursive, the space complexity is also O(log n)
Otherwise this works.
Comment on lines
+30
to
+34
| # Time Complexity: O(1) because we are doing a swap and deleting at the end | ||
| # (would be O of n if we were deleting from the front) | ||
| # Space Complexity: O(1) because we're not creating any new spaces in memory | ||
|
|
||
| def remove |
There was a problem hiding this comment.
This works but has similar time/space complexity issues to add.
| def empty? | ||
| raise NotImplementedError, "Method not implemented yet..." | ||
| @store.length == 0 ? true : false |
There was a problem hiding this comment.
Suggested change
| @store.length == 0 ? true : false | |
| return @store.length == 0 |
Comment on lines
+75
to
78
| # Time complexity: O(1) -- I *think* this code will stop running once | ||
| # count gets higher than 0 but I'm not certain | ||
| # Space complexity: O(1) | ||
| def empty? |
Comment on lines
+87
to
89
| # Time complexity: O(log n) because we're swapping max once per tree level | ||
| # Space complexity: O(log n) | ||
| def heap_up(index) |
| # stop if we're at the last leaf in the tree | ||
| return if @store[left_child_index].nil? && @store[right_child_index].nil? | ||
| # stop if both children are greater than or equal to parent | ||
| return if @store[left_child_index].key >= @store[index].key && @store |
There was a problem hiding this comment.
What if the right index child is not nil and it's less than @store[index]??? Looks like you missed an edge-case.
| # if parent is greater than left child, swap and look at next level -- | ||
| # need @store[index] conditional to stop code running after we've reached | ||
| # the bottom of the heap | ||
| if @store[index] && @store[index].key > @store[left_child_index].key |
There was a problem hiding this comment.
You also need to figure out which is smaller the left child or right child. Otherwise you'll do some unnecessary heap_downs.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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.
Heaps Practice
Congratulations! You're submitting your assignment!
Comprehension Questions
heap_up&heap_downmethods useful? Why?addmethod just swapped the first and last elements and removed the last, while theheap_uphelper took care of the heap reordering. Separation of concerns is good design!