Get the count of all subsets in array [1,2,3,4,6], that when summed, equal any element in the array. Input: [1,2,3,4,6] Output: 4 (The subsets are: [ 1, 2 ], [ 1, 3 ], [ 2, 4 ], [ 1, 2, 3 ] )

gistfile1.txt

function findSubsets(arr){
  var subsets = [],
		permutations = getPermutations(arr,2);
	console.log(findInArr(arr, permutations));
	return findInArr(arr, permutations).length;
}

function findInArr(arr, permutations){
	var returnArr = [], sum;
	for(var i = 0; i<permutations.length; i++){ // iterate through each permutation
		sum = 0; //initialize
		for(var j = 0; j < permutations[i].length; j++){ // sum each value in each permutation
			sum = sum + permutations[i][j];
		}
		if(arr.indexOf(sum) !== -1){ // if the sum exists in the given array, that's good
			returnArr.push(permutations[i]);
		}
	}
	return returnArr;
}

function getPermutations(a, min) {
    var fn = function(n, src, got, all) {
        if (n == 0) {
            if (got.length > 0) {
                all[all.length] = got;
            }
            return;
        }
        for (var j = 0; j < src.length; j++) {
            fn(n - 1, src.slice(j + 1), got.concat([src[j]]), all);
        }
        return;
    }
    var all = [];
    for (var i = min; i < a.length; i++) {
        fn(i, a, [], all);
    }
    all.push(a);
    return all;
}

console.log(findSubsets([1,2,3,4,6]));