Since the vast majority of recent problems are how to hack Cody, here's another one, with an even more malformed test suite than the original singularity.
Good luck hacking this one.
One interesting spin is: can you solve this problem using a freepass?
OK.
It will, but will the freepass work again if I rescore the solution? :-)
Determine if a Given Number is a Triangle Number
276 Solvers
234 Solvers
128 Solvers
Return the first and last character of a string
1157 Solvers
Convert a structure into a string
68 Solvers