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27 lines
645 B
Python
27 lines
645 B
Python
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# A binary search implementation to test if a number is in a list of elements
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def binary_search(a_list, item):
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"""
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>>> test_list = [0, 1, 2, 8, 13, 17, 19, 32, 42]
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>>> print(binary_search(test_list, 3))
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False
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>>> print(binary_search(test_list, 13))
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True
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"""
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if len(a_list) == 0:
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return False
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midpoint = len(a_list) // 2
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if a_list[midpoint] == item:
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return True
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if item < a_list[midpoint]:
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return binary_search(a_list[:midpoint], item)
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else:
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return binary_search(a_list[midpoint + 1 :], item)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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