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CheezItMan
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May 3, 2021
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It looks pretty good Christabel, I like the iterative methods, very efficient. However I think there are some hidden bugs in heap_down. Take a look at my comments and let me know if you have questions.
Consider:
heap.add(3, 3)
heap.add(6, 6)
heap.add(1, 1)Then if you try to remove things you'll get NoMethodError: undefined method key' for nil:NilClass`
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| # Time Complexity: O(n log n) where n is the number of elements in the given array | ||
| # Space Complexity: O(n) | ||
| def heap_sort(list) |
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This turns the array into a heap, it doesn't "sort" the array using a heap. So it's not quite the exercise.
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| # Time Complexity: O(log n) where n is the number of nodes in the heap | ||
| # Space Complexity: O(2) == O(1) | ||
| def add(key, value = key) |
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| # Time Complexity: O(log n) where n is the number of nodes in the heap | ||
| # Space Complexity: O(2) == O(1) | ||
| def remove() |
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| # Time complexity: O(1) ? I think the length of arrays is somehow cached or something in Ruby? If not, then O(n) where n is the number of elements in the array | ||
| # Space complexity: O(1) | ||
| def empty? |
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| # Time complexity: O(log n) where n is the number of nodes in the heap | ||
| # Space complexity: O(1) | ||
| def heap_up(current) |
| right_child = current * 2 + 2 | ||
| child = @store[left_child].key < @store[right_child].key ? left_child : right_child | ||
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| while @store[current].key > @store[child].key do |
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What happens if @store[left_child] is nil? I think this could cause an error.
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Heaps Practice
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Comprehension Questions
heap_up&heap_downmethods useful? Why?