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+ """
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+ This is pure python implementation of sentinel linear search algorithm
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+
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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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+
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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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+
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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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+
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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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+
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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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+
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+ >>> sentinel_linear_search([0, 5, 7, 10, 15], 15)
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+ 4
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+
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+ >>> sentinel_linear_search([0, 5, 7, 10, 15], 5)
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+ 1
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+
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+ >>> sentinel_linear_search([0, 5, 7, 10, 15], 6)
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+
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+ """
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+ sequence .append (target )
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+
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+ index = 0
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+ while sequence [index ] != target :
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+ index += 1
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+
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+ sequence .pop ()
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+
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+ if index == len (sequence ):
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+ return None
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+
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+ return index
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+
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+
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+ if __name__ == '__main__' :
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+ try :
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+ raw_input # Python 2
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+ except NameError :
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+ raw_input = input # Python 3
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+
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+ user_input = raw_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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+
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+ target_input = raw_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 ('{} found at positions: {}' .format (target , result ))
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+ else :
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+ print ('Not found' )
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