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40 lines
1.0 KiB
Python
40 lines
1.0 KiB
Python
"""
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File: top_k.py
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Created Time: 2023-06-10
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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 top_k_heap(nums: list[int], k: int) -> list[int]:
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"""ヒープに基づいて配列中の最大の k 個の要素を探す"""
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# 最小ヒープを初期化
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heap = []
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# 配列の先頭 k 個の要素をヒープに追加
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for i in range(k):
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heapq.heappush(heap, nums[i])
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# k+1 番目の要素から開始し、ヒープ長を k に保つ
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for i in range(k, len(nums)):
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# 現在の要素がヒープ先頭より大きければ、ヒープ先頭を取り出して現在の要素を追加する
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if nums[i] > heap[0]:
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heapq.heappop(heap)
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heapq.heappush(heap, nums[i])
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return heap
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"""Driver Code"""
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if __name__ == "__main__":
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nums = [1, 7, 6, 3, 2]
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k = 3
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res = top_k_heap(nums, k)
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print(f"最大の {k} 個の要素は")
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print_heap(res)
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