TheAlgorithms-Python

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"""
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This is pure Python implementation of sentinel linear search algorithm
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For doctests run following command:
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python -m doctest -v sentinel_linear_search.py
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or
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python3 -m doctest -v sentinel_linear_search.py
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For manual testing run:
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python sentinel_linear_search.py
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"""
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def sentinel_linear_search(sequence, target):
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    """Pure implementation of sentinel linear search algorithm in Python
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    :param sequence: some sequence with comparable items
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    :param target: item value to search
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    :return: index of found item or None if item is not found
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    Examples:
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    >>> sentinel_linear_search([0, 5, 7, 10, 15], 0)
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    0
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    >>> sentinel_linear_search([0, 5, 7, 10, 15], 15)
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    4
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    >>> sentinel_linear_search([0, 5, 7, 10, 15], 5)
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    1
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    >>> sentinel_linear_search([0, 5, 7, 10, 15], 6)
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    """
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    sequence.append(target)
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    index = 0
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    while sequence[index] != target:
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        index += 1
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    sequence.pop()
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    if index == len(sequence):
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        return None
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    return index
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if __name__ == "__main__":
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    user_input = input("Enter numbers separated by comma:\n").strip()
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    sequence = [int(item) for item in user_input.split(",")]
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    target_input = input("Enter a single number to be found in the list:\n")
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    target = int(target_input)
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    result = sentinel_linear_search(sequence, target)
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    if result is not None:
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        print(f"{target} found at positions: {result}")
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    else:
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        print("Not found")
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