Get the sum of array items that are equal to the target (Subset sum)

Question

I need to get the sum of array items that are equal to the target. If the sum of array item will not equal to the target I would like to get the highest sum that is less tha

Answer 1

Very similar solution to yours, a bit unclear if it's helpful:

numbers = [4, 6, 8, 12, 4, 6, 6, 12, 4, 4];

var result = createSubsets(numbers, 12);

console.log('Result', JSON.stringify(result));

function createSubsets(numbers, target) {
    // filter out all items larger than target
    numbers = numbers.filter(function (value) {
        return value <= target;
    });

    // sort from largest to smallest
    numbers.sort(function (a, b) {
        return b - a;
    });

    // array with all the subsets
    var result = [];

    while (numbers.length > 0) {
        var i;
        var sum = 0;
        var addedIndices = [];

        // go from the largest to the smallest number and
        // add as many of them as long as the sum isn't above target
        for (i = 0; i < numbers.length; i++) {
            if (sum + numbers[i] <= target) {
                sum += numbers[i];
                addedIndices.push(i);
            }
        }

        // remove the items we summed up from the numbers array, and store the items to result
        // since we're going to splice the numbers array several times we start with the largest index
        // and go to the smallest to not affect index position with splice.
        var subset = [];
        for (i = addedIndices.length - 1; i >= 0; i--) {
            subset.unshift(numbers[addedIndices[i]]);
            numbers.splice(addedIndices[i], 1);
        }
        result.push(subset);
    }

    return result;
}

Produces array:

[12],[12],[8,4],[6,6],[6,4],[4,4]

There's no limit regarding the subset length. If you add one more 4 to the numbers array you will get result:

[12],[12],[8,4],[6,6],[6,4],[4,4,4]

JSFiddle: http://jsfiddle.net/kUELD/