Need to Optimize the function

Question

I'm working on this function that has to return all possible values of adding a and b n times for example if n = 1 then possible values would be a + a a + b and b + b. function below works but it's too slow and I want to optimize it. Any suggestions? Thanks a lot!

function processData(n, a, b){
  var ans = [0];
  for(var i = 0; i < n; i++){
    var temp = [];
    for(var j = 0; j < ans.length; j++){
      var aa = ans[j] + a;
      if(temp.includes(aa) === false){
       temp.push(aa);
      }
      var bb = ans[j] + b;
      if(temp.includes(bb) === false){
        temp.push(bb);
      }
    }
    ans = temp;
  }
  ans.sort(function(a, b){return a - b});
  return ans;
}

Answer 1

function processData(n, a, b) {
  var ans = [];
  if (a == b) {
    for (var i=0; i<n+1; i++) {
      ans.push(a * n);
    }
    return ans;
  } else if (a > b) {
    var temp = a;
    a = b;
    b = temp;
  }
  var diff = b - a;
  for (var i=0; i<n+1; i++) {
      ans.push(a * n + diff * i);
  }
  return ans;
}

Okay, this is by far the most efficient solution. I've just tested it on fiddle.

All other three solutions greatly outperform yours. Mine is better than @abc123's because there's no need for sorting and better than @georg's because there's no need for using set or sorting.

Answer 2

This is a proposal which gets the postions for a and b.

function combine(left, right) {

    function carry() {
        return c.reduceRight(function (r, _, i, o) {
            return r && !(o[i] = (o[i] + 1) % left.length);
        }, 1);
    }

    var c = Array.apply(null, { length: right.length }).map(function () { return 0; }),
        result = [];

    do {
        result.push(c.reduce(function (r, a, i) {
            r[left[a]].push(right[i]);
            return r;
        }, left.reduce(function (r, a) {
            r[a] = [];
            return r;
        }, {})));
    } while (!carry());
    return result;
}

console.log(combine(['a', 'b'], [1, 2, 3]));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Just to make a disclosure, the answer is one of mine, given to a more detailed question of kind of the same, but not exactly: Find all combinations of two arrays

Answer 3

Here is a concise ES6 function for it:

function processData(n, a, b) {
    let diff = Math.abs(b-a), sum = Math.min(a,b) * (n+1) - diff;
    return diff ? Array.from(Array(n+2), _ => sum += diff) : [sum]; 
}

console.log(processData(2, 3, 5));