Learn English – an alternative term for “Swiss arthe knife”

There are in fact very few cases where the customary demonym is root + -man— those you have named plus Irishman, Norseman, Welshman, Scotsman, and (obsolete, now considered offensive) Chinaman, and maybe a few others in Britain like Yorkshireman or Cornishman.

In the absence of a more established form, the demonym is usually the same as the adjectival form. Just as we would speak of an Indonesian, an Omani, or a New Zealander, we would speak of a Swiss.

It sounds abrupt, even to this native speaker, not only because it is monosyllabic (e.g. calling someone a Japanese also seems off), but because in today's politically correct age, referring to someone solely by their nationality or ethnicity is potentially problematic. It would be preferable to use the demonymic adjective in conjunction with a noun; Swiss man would suffice.

In terms of programming, you can say one process is more efficient than the other because of less time complexity.