unfortunately this is not an efficiency optimization. the intent appears to be to match EITHER all-alpha OR all-numeric strings. the regex, as given, would mat

unfortunately this is not an efficiency optimization. the intent appears to be to match EITHER all-alpha OR all-numeric strings. the regex, as given, would match both "&()ABC" and "5673%$^#" and "123ABC" but NOT "ABC123" what should be a simple concept is defeated and confusion ensues. the correct formulation should have been ^[0-9]+$|^[A-Z]+$ or (judging from the example input and output samples) [0-9]+|[A-Z]+