sum problem

gistfile1.js

var solve = function(k,arr){
    var sums = {};
    var sum = function(a){
        var s = 0;
        for(var j = 0 ; j < a.length ; j++){
            s += a[j];
        }
        return s;
    };
    length = arr.length;
    for(var i = 0 ; i < length ; i++){
        sums[sum(arr)] = true;
        arr.shift();
    }
    console.log(true == sums[k] ? k+"? YES" : k+"? NO");
};

solve(13,[1,2,4,7]);
solve(15,[1,2,4,7]);