2016 Update

Task/Hofstadter-Figure-Figure-sequences/CoffeeScript/hofstadter-figure-figure-sequences.coffee

@@ -0,0 +1,26 @@
+R = [ null, 1 ]
+S = [ null, 2 ]
+
+extend_sequences = (n) ->
+  current = Math.max(R[R.length - 1], S[S.length - 1])
+  i = undefined
+  while R.length <= n or S.length <= n
+    i = Math.min(R.length, S.length) - 1
+    current += 1
+    if current == R[i] + S[i]
+      R.push current
+    else
+      S.push current
+
+ff = (X, n) ->
+    extend_sequences n
+    X[n]
+
+console.log 'R(' + i + ') = ' + ff(R, i) for i in [1..10]
+int_array = ([1..40].map (i) -> ff(R, i)).concat [1..960].map (i) -> ff(S, i)
+int_array.sort (a, b) -> a - b
+
+for i in [1..1000]
+  if int_array[i - 1] != i
+    throw 'Something\'s wrong!'
+console.log '1000 integer check ok.'