cb-easy-17.js

function ArrayAdditionI(arr) { 
  
  var valMap = {}; // Cache sums
  arr.sort(function(a,b) { return a - b;});
  var largestNum = arr.pop();
  for (var i = 0; i < arr.length; i++) {
    var combos = Object.keys(valMap);
    for (var j = 0; j < combos.length; j++) {
      var newCombo = arr[i] + (+combos[j]);
      if (newCombo === largestNum) return "true";
      valMap[newCombo] = true;
    }
    // Include current val in our set
    valMap[arr[i]] = true;
  }
  return "false";
}