You are given two integers x and y and array a of n integers. x is initially equal to zero. For every element in the a you can either add it to x, or you can subtract it from x. You have to tell whether you can make the number x equal to the number y by any means. An O(n^2) approach would work too. Additionally all the elements of a are <=300, I don't know if it's of any use.

Thanks.