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25 lines
806 B
Python
25 lines
806 B
Python
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def binary_search_rotation(nums: list[int]) -> int:
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"""二分查找左边界（双闭区间）"""
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# 初始化双闭区间 [0, n-1] ，即 i, j 分别指向数组首元素、尾元素
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i, j = 0, len(nums) - 1
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while True:
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m = (i + j) // 2 # 计算中点索引 m
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if nums[m] < nums[j]:
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j = m # 此情况说明 target 在区间 [m+1, j] 中
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elif nums[m] > nums[j]:
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i = m + 1 # 此情况说明 target 在区间 [i, m-1] 中
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else:
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return i # 此情况说明 i == j == m ，找到旋转点
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"""Driver Code"""
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if __name__ == "__main__":
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nums: list[int] = [23, 67, 70, 92, 1, 3, 6, 8, 12, 15]
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# 二分查找左边界
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index_left = binary_search_rotation(nums)
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print("数组旋转点的索引 = ", index_left)
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