Initial data commit

Task/Hailstone-sequence/JavaScript/hailstone-sequence-4.js

@@ -0,0 +1,50 @@
+(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);
+
+})();