(function () {

  function memoizedHailstone() {
    var dctMemo = {};

    return function hailstone(n) {
      var value = dctMemo[n];

      if (typeof value === "undefined") {
        dctMemo[n] = value = (n === 1) ?
          [1] : ([n].concat(hailstone(n % 2 ? n * 3 + 1 : n / 2)));
      }
      return value;
    }
  }

  // Derived a memoized version of the function,
  // which can reuse previously calculated paths
  var fnCollatz = memoizedHailstone();

  // Iterative version of range
  // [m..n]
  function range(m, n) {
    var a = Array(n - m + 1),
      i = n + 1;
    while (i--) a[i - 1] = i;
    return a;
  }

  // Fold/reduce over an array to find the maximum length
  function longestBelow(n) {
    return range(1, n).reduce(
      function (a, x, i) {
        var lng = fnCollatz(x).length;

        return lng > a.l ? {
          n: i + 1,
          l: lng
        } : a

      }, {
        n: 0,
        l: 0
      }
    )
  }

  return longestBelow(100000);

})();