From 3c69861ab71fc2b9ea00cafa45abf6f64cdc8305 Mon Sep 17 00:00:00 2001
From: Grzegorz Kucmierz <gkucmierz@gmail.com>
Date: Tue, 19 Nov 2019 10:29:52 +0100
Subject: [PATCH] Perimeter of squares in a rectangle

---
 perimeter-of-squares-in-a-rectangle/index.js | 23 ++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 perimeter-of-squares-in-a-rectangle/index.js

diff --git a/perimeter-of-squares-in-a-rectangle/index.js b/perimeter-of-squares-in-a-rectangle/index.js
new file mode 100644
index 0000000..3f13ffc
--- /dev/null
+++ b/perimeter-of-squares-in-a-rectangle/index.js
@@ -0,0 +1,23 @@
+// https://www.codewars.com/kata/perimeter-of-squares-in-a-rectangle/javascript
+
+const perimeter = (() => {
+  const map = new WeakMap();
+  const f = n => {
+    if (n in map) return map[n];
+    if (n === 0) return fib(n) * 4;
+    return map[n] = 4 * fib(n) + f(n-1);
+  };
+  return f;
+})();
+
+// https://gist.github.com/gkucmierz/9bc8126bdb8d42a17ccb25f81bf02519
+const fib = ((fst, snd) => {
+  const map = new WeakMap();
+  const f = n => {
+    if (n in map) return map[n];
+    if (n === 0) return fst;
+    if (n === 1) return snd;
+    return map[n] = f(n-1) + f(n-2);
+  };
+  return f;
+})(1, 1);