subset sum

subsetSum.js

/* 
You are given an array of integers ARR and an integer SUM.

Your task is to find the number of subsets of the array ARR, such that the sum of their elements equals SUM

Example:

SubsetSum([1,2,3,4,5], 5) = 3
These subsets are [1,4], [2,3] and [5].
SubsetSum([1,2,3,4,-5], 0) = 3
These subsets are [1,4,-5], [2,3,-5] and [].

*/
SubsetSum = (x, u) => {
    p = []
    for (m = 1; m < 1 << x.length; m++) p[m] = ( x.filter((v, i) => ((m >> i) & 1) == 1) )
    r = p.filter( b => b.reduce((a,b) => a+b) == u).length
    return u == 0 ? r+1 : r 
}