euler problem 19

eulerproblem19

(ns euler.problem19)

(defn isleapyear?[yr]
  (and (not (zero? (mod yr 100))) (= 0 (mod yr 4))))

(def nonleapmonths [31 28 31 30 31 30 31 31 30 31 30 31])
(def leapmonths     [31 29 31 30 31 30 31 31 30 31 30 31])

(defn getfirstmonthdays [yr]
  (loop [index 0
         yr yr
         firstdaysofmonths [1]]
    (let [months (if (isleapyear? yr) leapmonths nonleapmonths)   ]
      (if (= 1188 index)
        firstdaysofmonths
        (recur (inc index) (+ yr (/ index 12)) (conj firstdaysofmonths (+ (peek firstdaysofmonths )(months  (mod index 12)))))))))

(defn countsundaysonfirstonmonth [firstsunday firsdaysofmonth]
  (count (filter #(or (= firstsunday %) (= firstsunday (mod % 7))) firsdaysofmonth)) )


(countsundaysonfirstonmonth 4 (getfirstmonthdays 1901))

gistfile1.txt

(ns euler.problem19)

(defn isleapyear?[yr]
  (and (not (zero? (mod yr 100))) (= 0 (mod yr 4))))

(def nonleapmonths [31 28 31 30 31 30 31 31 30 31 30 31])
(def leapmonths     [31 29 31 30 31 30 31 31 30 31 30 31])

(defn getfirstmonthdays [yr]
  (loop [index 0
         yr yr
         firstdaysofmonths [1]]
    (let [months (if (isleapyear? yr) leapmonths nonleapmonths)   ]
      (if (= 1188 index)
        firstdaysofmonths
        (recur (inc index) (+ yr (/ index 12)) (conj firstdaysofmonths (+ (peek firstdaysofmonths )(months  (mod index 12)))))))))

(defn countsundaysonfirstonmonth [firstsunday firsdaysofmonth]
  (count (filter #(or (= firstsunday %) (= firstsunday (mod % 7))) firsdaysofmonth)) )


(countsundaysonfirstonmonth 4 (getfirstmonthdays 1901))