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* Retranslate the complete English edition from Simplified Chinese * Polish three English explanations after reader-focused review
72 lines
2.1 KiB
Python
72 lines
2.1 KiB
Python
"""
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File: heap.py
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Created Time: 2023-02-23
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Author: krahets (krahets@163.com)
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"""
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import sys
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from pathlib import Path
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sys.path.append(str(Path(__file__).parent.parent))
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from modules import print_heap
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import heapq
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def test_push(heap: list, val: int, flag: int = 1):
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heapq.heappush(heap, flag * val) # Push an element onto the heap
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print(f"\nAfter pushing element {val} onto the heap:")
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print_heap([flag * val for val in heap])
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def test_pop(heap: list, flag: int = 1):
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val = flag * heapq.heappop(heap) # Pop the top element from the heap
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print(f"\nAfter popping top element {val} from the heap:")
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print_heap([flag * val for val in heap])
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"""Driver code"""
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if __name__ == "__main__":
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# Initialize a min heap
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min_heap, flag = [], 1
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# Initialize a max heap
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max_heap, flag = [], -1
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print("\nThe following example uses a max heap")
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# Python's heapq module implements a min heap by default
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# Negate each element before pushing it onto the heap to reverse the ordering and implement a max heap
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# In this example, flag = 1 represents a min heap and flag = -1 represents a max heap
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# Push an element onto the heap
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test_push(max_heap, 1, flag)
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test_push(max_heap, 3, flag)
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test_push(max_heap, 2, flag)
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test_push(max_heap, 5, flag)
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test_push(max_heap, 4, flag)
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# Get the top element of the heap
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peek: int = flag * max_heap[0]
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print(f"\nTop element of the heap: {peek}")
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# Pop the top element from the heap
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test_pop(max_heap, flag)
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test_pop(max_heap, flag)
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test_pop(max_heap, flag)
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test_pop(max_heap, flag)
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test_pop(max_heap, flag)
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# Get the heap size
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size: int = len(max_heap)
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print(f"\nNumber of elements in the heap: {size}")
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# Check whether the heap is empty
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is_empty: bool = not max_heap
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print(f"\nIs the heap empty: {is_empty}")
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# Build a heap from an input list
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# The time complexity is O(n), not O(nlogn)
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min_heap = [1, 3, 2, 5, 4]
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heapq.heapify(min_heap)
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print("\nAfter building a min heap from the input list:")
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print_heap(min_heap)
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