> Because this kind of problem is an interesting way to put yourself searching all the API of the language in order to solve the challenge in the more elegant/concise way you currently can.
Bullcrap. APIs are either going to be irrelevant for solving an algorithm, or will simply do the job for you. "Implementing an algorithm" usually means writing it from scratch using simple data structures, primitives and basic flow control constructs.
> Because this kind of problem is an interesting way to put yourself searching all the API of the language in order to solve the challenge in the more elegant/concise way you currently can.
Bullcrap. APIs are either going to be irrelevant for solving an algorithm, or will simply do the job for you. "Implementing an algorithm" usually means writing it from scratch using simple data structures, primitives and basic flow control constructs.