You are given some resource strings which contain letters and the special substitution command
%s</syntaxhighlight>. Each error message in the system is derived starting from the string "
%s</syntaxhighlight>" consisting only of the substitution symbol, and then by successively replacing occurrences of
%s</syntaxhighlight> by resource strings. You are to find how many different ways a given error message can be derived. (See link for a more precise definition of how error messages can be built.)
From TopCoder Single Round Match 342.
- If the resource strings are
- Then "one and one and one" can be generated in 2 ways.