From 613674a7daf9a521b4e38340f54a46279a882fce Mon Sep 17 00:00:00 2001
From: Nat Lasseter <Nat Lasseter user@4574.co.uk>
Date: Wed, 21 Feb 2018 09:04:45 +0000
Subject: Memoised fib

---
 fib.pr | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 fib.pr

diff --git a/fib.pr b/fib.pr
new file mode 100644
index 0000000..5d683ad
--- /dev/null
+++ b/fib.pr
@@ -0,0 +1,42 @@
+#fib(0) is
+# 1
+#end
+#fib(1) is
+# 1
+#end
+#fib(n) is
+# fib(n-1) + fib(n-2)
+#end
+
+#puts fib(100)
+
+require 'yaml'
+$memo = {}
+if File.exists?("memofib.yaml") then
+  File.open("memofib.yaml", "r") do |f|
+    mem = YAML.load(f.read)
+    $memo = mem if mem
+  end
+end
+
+memofib(0) is
+  1
+end
+memofib(1) is
+  1
+end
+memofib(n) is
+  if $memo.include?(n) then
+    $memo[n]
+  else
+    f = memofib(n-1) + memofib(n-2)
+    $memo[n] = f
+  end
+end
+
+puts memofib(1000)
+
+File.open("memofib.yaml", "w") do |f|
+  f.write YAML.dump($memo)
+  f.flush
+end
-- 
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