Scissors - Aida R.#49
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CheezItMan
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Feb 1, 2022
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Thanks for getting this in Aida, just 1 method not completed. Take a look at my feedback and let me know what questions you have.
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| def heap_sort(list): | ||
| """ This method uses a heap to sort an array. | ||
| Time Complexity: ? | ||
| Space Complexity: ? | ||
| Time Complexity: O(n) | ||
| Space Complexity: O(n) | ||
| """ |
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👍 However the time complexity is O(n log n) because you are adding n elements to the heap and each addition takes O(log n) time.
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| def add(self, key, value = None): | ||
| """ This method adds a HeapNode instance to the heap | ||
| If value == None the new node's value should be set to key | ||
| Time Complexity: ? | ||
| Space Complexity: ? | ||
| Time Complexity: O(log n) | ||
| Space Complexity: O(1) |
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👍 However the space complexity is O(log n) due to heap_up's recursive call stack.
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| def remove(self): | ||
| """ This method removes and returns an element from the heap | ||
| maintaining the heap structure | ||
| Time Complexity: ? | ||
| Space Complexity: ? | ||
| Time Complexity: O(log n) | ||
| Space Complexity: O(1) | ||
| """ |
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| def empty(self): | ||
| """ This method returns true if the heap is empty | ||
| Time complexity: ? | ||
| Space complexity: ? | ||
| Time complexity: O(1) | ||
| Space complexity: O(1) | ||
| """ |
| return len(self.store) == 0 | ||
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| def heap_up(self, index): |
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| def heap_down(self, index): | ||
| """ This helper method takes an index and | ||
| moves the corresponding element down the heap if it's | ||
| larger than either of its children and continues until | ||
| the heap property is reestablished. | ||
| """ | ||
| pass | ||
| raise NotImplementedMethodError("Method hasn't been implemented yet!") |
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The trick is:
- Determine if there are left and right children using the formula.
- Find the minimum child
- if the current node is less than the minimum child swap them and call
heap_downon the new current node
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Heaps Practice
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Comprehension Questions
heap_up&heap_downmethods useful? Why?