A-M baby

Task/Fibonacci-sequence/Clojure/fibonacci-sequence-1.clj

@@ -0,0 +1,2 @@
+(defn fibs []
+  (map first (iterate (fn [[a b]] [b (+ a b)]) [0 1])))

Task/Fibonacci-sequence/Clojure/fibonacci-sequence-2.clj

@@ -0,0 +1 @@
+(nth (fibs) 5)

Task/Fibonacci-sequence/Clojure/fibonacci-sequence-3.clj

@@ -0,0 +1,6 @@
+(defn fibs []
+  (map first ;; throw away the "metadata" (see below) to view just the fib numbers
+       (iterate ;; create an infinite sequence of [prev, curr] pairs
+         (fn [[a b]] ;; to produce the next pair, call this function on the current pair
+           [b (+ a b)]) ;; new prev is old curr, new curr is sum of both previous numbers
+         [0 1]))) ;; recursive base case: prev 0, curr 1

Task/Fibonacci-sequence/Clojure/fibonacci-sequence-4.clj

@@ -0,0 +1 @@
+(def fib (lazy-cat [0 1] (map + fib (rest fib))))

Task/Fibonacci-sequence/Clojure/fibonacci-sequence-5.clj

@@ -0,0 +1,2 @@
+user> (take 10 fib)
+(0 1 1 2 3 5 8 13 21 34)

Task/Fibonacci-sequence/Clojure/fibonacci-sequence-6.clj

@@ -0,0 +1,18 @@
+;; max is which fib number you'd like computed (0th, 1st, 2nd, etc.)
+;; n is which fib number you're on for this call (0th, 1st, 2nd, etc.)
+;; j is the nth fib number (ex. when n = 5, j = 5)
+;; i is the nth - 1 fib number
+(defn- fib-iter
+  [max n i j]
+  (if (= n max)
+    j
+    (recur max
+           (inc n)
+           j
+           (+ i j))))
+
+(defn fib
+  [max]
+  (if (< max 2)
+    max
+    (fib-iter max 1 0N 1N)))