51 lines
1.1 KiB
Python
51 lines
1.1 KiB
Python
"""
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归并排序 — 分治法的经典应用
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时间复杂度 O(n log n)，空间复杂度 O(n)
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"""
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def merge(arr, left, mid, right):
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"""合并两个有序子数组"""
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# 创建临时数组
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L = arr[left:mid + 1]
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R = arr[mid + 1:right + 1]
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i = j = 0
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k = left
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# 合并两个有序数组
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while i < len(L) and j < len(R):
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if L[i] <= R[j]:
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arr[k] = L[i]
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i += 1
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else:
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arr[k] = R[j]
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j += 1
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k += 1
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# 复制剩余元素
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while i < len(L):
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arr[k] = L[i]
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i += 1
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k += 1
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while j < len(R):
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arr[k] = R[j]
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j += 1
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k += 1
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def merge_sort(arr, left, right):
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"""归并排序主函数"""
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if left < right:
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mid = (left + right) // 2
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merge_sort(arr, left, mid)
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merge_sort(arr, mid + 1, right)
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merge(arr, left, mid, right)
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def sort(arr):
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merge_sort(arr, 0, len(arr) - 1)
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if __name__ == "__main__":
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data = [38, 27, 43, 3, 9, 82, 10]
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print("排序前:", data)
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sort(data)
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print("排序后:", data)
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