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solve exercises 1-26 #736

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4 changes: 2 additions & 2 deletions .travis.yml
Original file line number Diff line number Diff line change
@@ -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:
Expand Down
134 changes: 106 additions & 28 deletions src/recursion.clj
Original file line number Diff line number Diff line change
@@ -1,85 +1,164 @@
(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 (nil? (fnext coll))
(first coll)
(my-last (rest coll))))

(defn max-element [a-seq]
:-)
(let [[head & tail] a-seq]
(if (empty? tail)
head
(recur (cons (max head (first tail)) (rest tail))))))

(defn seq-max [seq-1 seq-2]
[:-])
(if (> (count seq-1) (count seq-2))
seq-1
seq-2))

(defn longest-sequence [a-seq]
[:-])
(let [[head & tail] a-seq]
(if (empty? tail)
head
(recur (cons (seq-max head (first tail)) (rest tail))))))

(defn my-filter [pred? a-seq]
[:-])
(if (empty? a-seq)
a-seq
(let [head (first a-seq)
tail (rest a-seq)]
(if (pred? head)
(cons head (my-filter pred? tail))
(my-filter pred? tail)))))

(defn sequence-contains? [elem a-seq]
:-)
(cond
(empty? a-seq) false
(= elem (first a-seq)) true
:else (sequence-contains? elem (rest a-seq))))

(defn my-take-while [pred? a-seq]
[:-])
(cond
(empty? a-seq) a-seq
(pred? (first a-seq)) (cons (first a-seq) (my-take-while pred? (rest a-seq)))
:else '() ))

(defn my-drop-while [pred? a-seq]
[:-])
(cond
(empty? a-seq) a-seq
(not (pred? (first a-seq))) a-seq
:else (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
(not (= (first a-seq) (first b-seq))) false
:else (seq= (rest a-seq) (rest b-seq))))

(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]
:-)
(cond
(zero? n) 0
(zero? k) 1
(= k 1) n
:else (* n (power n (dec k)))))

(defn fib [n]
:-)
(cond
(zero? n) 0
(= n 1) 1
(> n 1) (+ (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]
[:-])
(if (empty? a-seq)
[[]]
(cons (sequence a-seq) (tails (rest a-seq)))))

(defn inits [a-seq]
[:-])
(if (empty? a-seq)
[[]]
(cons (sequence a-seq) (inits (pop a-seq)))))

(defn rotations [a-seq]
[:-])
(if (empty? a-seq)
[[]]
(map
(fn [n _]
(concat (drop n a-seq) (take n a-seq)))
(range (count a-seq)) a-seq)))

(defn my-frequencies-helper [freqs a-seq]
[:-])
(if (empty? a-seq)
freqs
(let [new-freqs (if (contains? freqs (first a-seq))
(assoc freqs (first a-seq) (inc (freqs (first a-seq))))
(assoc freqs (first a-seq) 1))]
(my-frequencies-helper new-freqs (rest a-seq)))))

(defn my-frequencies [a-seq]
[:-])
(my-frequencies-helper {} a-seq))

(defn un-frequencies [a-map]
[:-])
(if (empty? a-map)
'()
(let [a-key (first (first a-map))
a-val (second (first a-map))]
(concat (repeat a-val a-key) (un-frequencies (rest a-map))))))

(defn my-take [n coll]
[:-])
(cond
(empty? coll) '()
(zero? n) '()
:else (cons (first coll) (my-take (dec n) (rest coll)))))

(defn my-drop [n coll]
[:-])
(cond
(empty? coll) '()
(zero? n) coll
:else (my-drop (dec n) (rest coll))))

(defn halve [a-seq]
[:-])
(let [half (int (/ (count a-seq) 2))]
(vector (take half a-seq) (drop half 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
(seq-merge (merge-sort (first (halve a-seq)))
(merge-sort (second (halve a-seq))))))

(defn split-into-monotonics [a-seq]
[:-])
Expand All @@ -89,4 +168,3 @@

(defn powerset [a-set]
[:-])