@CBBBrother I think his method is pretty safe, considering he's not copying the vector for each stack frame but instead only the reference to that vector.

@yidui From what I understand, the function isn't tail recursive because the recursive call isn't the last operation performed by the function (last operation being the allocation of the new object). I don't really see how one could write it as a tail recursive funcion really...

Maybe use tail recursion can avoide this problem.