Using Recursion To Search All Combinations Of Elements In An Array Of Integers

I am working on this problem from Coderbyte using JS: Have the function ArrayAdditionI(arr) take the array of numbers stored in arr and return the string true if any combination of

Solution 1:

Your algorithm has a flaw. Your function looks only one step forward. You need to add loop inside to look over all rest values.

function ArrayAdditionI(arr) {
    // sorting the array to easily remove the biggest value
    // slice added to prevent original array modification
    var sArr = arr.slice().sort(function (a, b) { 
        return a - b;
    });
    // removing the biggest value
    var biggest = sArr.pop();
    function recursion(start, i) {
        var result = false;
        // looking over all rest values of array
        for (var j = i; j < sArr.length && !result; j++) {
            if (sArr[j] + start === biggest) {
                result = true;
            }
            else if (start + sArr[j] < biggest) {
                result = recursion(start + sArr[j], j + 1);
            }
        }
        return result;
    }
    return recursion(0, 0);
}

Solution 2:

function ArrayAdditionI (arr) {
    var sArr = arr.sort(function (a,b) {
        return a-b;
    });
    var biggest = sArr.pop();
    function recursion (start, indx) {
        if (start + sArr[indx] === biggest) {
            return true;
        }
        else if (sArr.length < indx) {
            return false;
        }
        else if (start + sArr[indx] < biggest) {
            return recursion(start + sArr[indx], indx + 1) || recursion(start, indx+1)
        }
        else {
            return false;
        }
    }
    return recursion(0,0);
}