Longest string of non repeating characters problem

longestNonRepeating.js

function longestNonRepeating(a, b, c) {
  list = [
    [a, 'a'],
    [b, 'b'],
    [c, 'c']
  ].sort()

  if (list[2][0] > list[1][0] + list[0][0] + 1) {
    return "none"
  }

  var result = ""
  while (list[2][0] > 0) {
    
    result += list[2][1]
    --list[2][0]

    if (list[1][0] > 0) {
      result += list[1][1]
      --list[1][0]
    }

    list.sort()
  }

  return result
}