Fire - Jing #20
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Fire - Jing #20
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CheezItMan
reviewed
May 6, 2021
| def heapsort(list) |
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Also you add things into a heap, but in the internal structure the items are not sorted. They're maintained in heap order with the parent smaller than it's children. You have to REMOVE elements from the heap 1-by-1 to be guaranteed to get it into order.
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| # Time Complexity: O(logn) | ||
| # Space Complexity: O(1) | ||
| def add(key, value = key) |
lib/min_heap.rb
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| if @store.empty? | ||
| @store << HeapNode.new(key, value) |
lib/min_heap.rb
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| def remove() | ||
| raise NotImplementedError, "Method not implemented yet..." | ||
| min = @store.min_by {|node| node.key} |
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This is a linear search, you're totally losing the advantage of a Heap here!
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| # Time complexity: O(0) | ||
| # Space complexity: O(0) | ||
| def empty? |
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| # Time complexity: O(logn) | ||
| # Space complexity: O(0) | ||
| def heap_up(index) |
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| # This helper method takes an index and | ||
| # moves it up the heap if it's smaller | ||
| # than it's parent node. | ||
| def heap_down(index) |
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This isn't working because you've got to:
- Check the both left and right child
- And swap with the smaller of the two, if needed
- Consider the case where there is a left child and not a right child
added 2 commits
May 6, 2021 12:04
CheezItMan
approved these changes
May 7, 2021
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| swap(index, index * 2 + 1) | ||
| swap(index, index * 2 + 2) if @store[index * 2 + 2] != nil && @store[index].key > @store[index * 2 + 2].key |
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Heaps Practice
Congratulations! You're submitting your assignment!
Comprehension Questions
heap_up&heap_downmethods useful? Why?