How do I write a generic memoize function?

Question

I\'m writing a function to find triangle numbers and the natural way to write it is recursively:

function triangle (x)
   if x == 0 then return 0 end
   retu         


        

Answer 1

Recursion isn't necessary. The nth triangle number is n(n-1)/2, so...

public int triangle(final int n){
   return n * (n - 1) / 2;
}