Most exercises are declared using List, which is a linked list with no cached size nor optimized indexed access, as a direct translation fom a java exercise. There are exercises which are plain impossible to solve because the solution is required to be returned as List[List[Int]] for which there is a memory limit that forbids the instantiation.

Exercises for trees have use the same TreeNode structure which is hilariously wrong, with two public visible mutable fields (one called value and another one called _value).

As a language being supported, it feels like the person who added the exercises didn't spend even 5 minutes on google learning the language syntax.

Please fix this.