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

Please don't recurse this. Either use the x*(x+1)/2 formula or simply iterate the values and memoize as you go.

int[] memo = new int[n+1];
int sum = 0;
for(int i = 0; i <= n; ++i)
{
  sum+=i;
  memo[i] = sum;
}
return memo[n];