c# - Parameter regex -

i need creating regex validating parameter string.

parameter string consists of 2 optional groups of explicit characters. first group can contain 1 occurrence of p, o, z characters (order doesn't matter). second group has same restrictions can contain characters t, c, p, m. if both groups presented, need delimited single space character.

so valid strings are:

p t po t ozp ct p tcmp p pz t tp 

etc.

i don't think regex solution here, because have quite complicated:

regex regexobj = new regex(     @"^               # start of string     (?:               # start non-capturing group:      ([poz])          # match , capture 1 of [poz] in group 1      (?![poz]*\1)     # assert that character doesn't show again     )*                # repeat number of times (including zero)     (?:               # start non-capturing group:      (?<!^)           # assert we're not @ start of string      \                # match space      (?!$)            # assert we're not @ end of string     )?                # make group optional.     (?<!              # assert we're not right after...      [poz]            # 1 of [poz] (i. e. make sure there's space)      (?!$)            # unless we're @ end of string.     )                 # end of negative lookahead assertion     (?:               # start yet non-capturing group:      ([tcpm])         # match , capture 1 of [tcpm] in group 2      (?![tcpm]*\2)    # assert that character doesn't show again     )*                # repeat number of times (including zero)     $                 # end of string",      regexoptions.ignorepatternwhitespace);