44 lines
1.1 KiB
Python
44 lines
1.1 KiB
Python
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"""
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二分查找 — 在有序数组中查找目标值
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时间复杂度 O(log n)
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"""
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def binary_search_recursive(arr, target, left, right):
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"""递归版二分查找"""
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if left > right:
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return -1
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mid = left + (right - left) // 2
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if arr[mid] == target:
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return mid
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elif arr[mid] > target:
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return binary_search_recursive(arr, target, left, mid - 1)
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else:
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return binary_search_recursive(arr, target, mid + 1, right)
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def binary_search_iterative(arr, target):
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"""迭代版二分查找"""
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left, right = 0, len(arr) - 1
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while left <= right:
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mid = left + (right - left) // 2
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if arr[mid] == target:
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return mid
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elif arr[mid] > target:
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right = mid - 1
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else:
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left = mid + 1
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return -1
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if __name__ == "__main__":
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arr = [1, 3, 5, 7, 9, 11, 13, 15]
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target = 7
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idx1 = binary_search_recursive(arr, target, 0, len(arr) - 1)
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idx2 = binary_search_iterative(arr, target)
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print(f"数组: {arr}")
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print(f"查找 {target}: 递归版结果索引={idx1}, 迭代版结果索引={idx2}")
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