Fix

.travis.yml

@@ -1,6 +1,6 @@
 language: clojure
-lein: lein2
-script: lein2 midje :config .midje-grading-config.clj
+lein: lein
+script: lein midje :config .midje-grading-config.clj
 jdk:
   - openjdk7
 notifications:

src/recursion.clj

@@ -1,86 +1,162 @@
 (ns recursion)
 
 (defn product [coll]
-  :-)
+  (if (empty? coll)
+    1
+    (* (first coll)
+       (product (rest coll)))))
 
 (defn singleton? [coll]
-  :-)
+  (and (not (empty? coll))
+       (empty? (rest coll))))
 
 (defn my-last [coll]
-  :-)
+  (if (empty? (rest coll))
+    (first coll)
+    (my-last (rest coll))))
 
 (defn max-element [a-seq]
-  :-)
+  (if (or (singleton? a-seq) (empty? a-seq))
+    (first a-seq)
+    (max (first a-seq)
+         (max-element (rest a-seq)))))
 
 (defn seq-max [seq-1 seq-2]
-  [:-])
+  (if (> (count seq-1) (count seq-2))
+    seq-1
+    seq-2))
 
 (defn longest-sequence [a-seq]
-  [:-])
+  (if (empty? a-seq)
+    nil
+    (seq-max (first a-seq) (longest-sequence (rest a-seq)))))
 
 (defn my-filter [pred? a-seq]
-  [:-])
+  (if (empty? a-seq)
+    a-seq
+    (if (pred? (first a-seq))
+      (cons (first a-seq) (my-filter pred? (rest a-seq)))
+      (my-filter pred? (rest a-seq)))))
 
 (defn sequence-contains? [elem a-seq]
-  :-)
+  (if (empty? a-seq)
+    false
+    (if (= elem (first a-seq))
+      true
+      (sequence-contains? elem (rest a-seq)))))
 
 (defn my-take-while [pred? a-seq]
-  [:-])
+  (if (empty? a-seq)
+    a-seq
+    (if (not (pred? (first a-seq)))
+      '()
+      (cons (first a-seq) (my-take-while pred? (rest a-seq))))))
 
 (defn my-drop-while [pred? a-seq]
-  [:-])
+  (if (empty? a-seq)
+    '()
+    (if (not (pred? (first a-seq)))
+      a-seq
+      (my-drop-while pred? (rest a-seq)))))
+
 
 (defn seq= [a-seq b-seq]
-  :-)
+  (cond
+    (and (empty? a-seq) (empty? b-seq))
+      true
+    (or (empty? a-seq) (empty? b-seq))
+      false
+    (= (first a-seq) (first b-seq))
+      (seq= (rest a-seq) (rest b-seq))
+    :else false))
 
 (defn my-map [f seq-1 seq-2]
-  [:-])
+  (if (or (empty? seq-1) (empty? seq-2))
+    '()
+    (cons (f (first seq-1) (first seq-2))
+          (my-map f (rest seq-1) (rest seq-2)))))
 
 (defn power [n k]
-  :-)
+  (if (zero? k)
+    1
+    (* n (power n (dec k)))))
 
 (defn fib [n]
-  :-)
+  (cond
+    (<= n 0) 0
+    (= n 1) 1
+    :else (+ (fib (- n 1))
+             (fib (- n 2)))))
 
 (defn my-repeat [how-many-times what-to-repeat]
-  [:-])
+  (if (<= how-many-times 0)
+    '()
+    (cons what-to-repeat (my-repeat (dec how-many-times) what-to-repeat))))
 
 (defn my-range [up-to]
-  [:-])
+  (if (zero? up-to)
+    '()
+    (cons (dec up-to) (my-range (dec up-to)))))
 
 (defn tails [a-seq]
-  [:-])
+  (cons a-seq (if (empty? a-seq)
+                '()
+                (tails (rest a-seq)))))
 
 (defn inits [a-seq]
-  [:-])
+  (reverse (map reverse (tails (reverse a-seq)))))
 
 (defn rotations [a-seq]
-  [:-])
+  (if (empty? a-seq)
+    '(())
+    (rest (map concat (tails a-seq) (inits a-seq)))))
 
 (defn my-frequencies-helper [freqs a-seq]
-  [:-])
+  (if (empty? a-seq)
+    freqs
+    (let [cur-elem (first a-seq)
+          new-freqs (assoc freqs
+                           cur-elem
+                           (if (contains? freqs cur-elem)
+                             (inc (get freqs cur-elem))
+                             1))]
+      (my-frequencies-helper new-freqs (rest a-seq)))))
 
 (defn my-frequencies [a-seq]
-  [:-])
+  (my-frequencies-helper {} a-seq))
 
 (defn un-frequencies [a-map]
-  [:-])
+  (mapcat (fn [[key value]] (repeat value key)) a-map))
 
 (defn my-take [n coll]
-  [:-])
+  (if (or (zero? n) (empty? coll))
+    '()
+    (cons (first coll) (my-take (dec n) (rest coll)))))
 
 (defn my-drop [n coll]
-  [:-])
+  (if (zero? n)
+    coll
+    (my-drop (dec n) (rest coll))))
 
 (defn halve [a-seq]
-  [:-])
+  (let [pivot (int (/ (count a-seq) 2))]
+    [(my-take pivot a-seq) (my-drop pivot a-seq)]))
 
 (defn seq-merge [a-seq b-seq]
-  [:-])
+  (cond
+    (and (empty? a-seq) (empty? b-seq)) '()
+    (empty? a-seq) b-seq
+    (empty? b-seq) a-seq
+    :else
+      (if (< (first a-seq) (first b-seq))
+        (cons (first a-seq) (seq-merge (rest a-seq) b-seq))
+        (cons (first b-seq) (seq-merge a-seq (rest b-seq))))))
 
 (defn merge-sort [a-seq]
-  [:-])
-
+  (if (<= (count a-seq) 1)
+    a-seq
+    (let [[left right] (halve a-seq)]
+      (seq-merge (merge-sort left) (merge-sort right)))))
 (defn split-into-monotonics [a-seq]
   [:-])