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72 lines
1.9 KiB
Python
72 lines
1.9 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) # 元素入堆
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print(f"\n元素 {val} 入堆后")
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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) # 堆顶元素出堆
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print(f"\n堆顶元素 {val} 出堆后")
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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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# 初始化小顶堆
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min_heap, flag = [], 1
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# 初始化大顶堆
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max_heap, flag = [], -1
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print("\n以下测试样例为大顶堆")
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# Python 的 heapq 模块默认实现小顶堆
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# 考虑将“元素取负”后再入堆，这样就可以将大小关系颠倒，从而实现大顶堆
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# 在本示例中，flag = 1 时对应小顶堆，flag = -1 时对应大顶堆
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# 元素入堆
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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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# 获取堆顶元素
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peek: int = flag * max_heap[0]
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print(f"\n堆顶元素为 {peek}")
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# 堆顶元素出堆
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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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# 获取堆大小
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size: int = len(max_heap)
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print(f"\n堆元素数量为 {size}")
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# 判断堆是否为空
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is_empty: bool = not max_heap
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print(f"\n堆是否为空 {is_empty}")
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# 输入列表并建堆
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# 时间复杂度为 O(n) ，而非 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("\n输入列表并建立小顶堆后")
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print_heap(min_heap)
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