Darius Liddell djtrack16

Stanford CS. Ruby. Functional Programming Enthusiast. Slow Traveller. Cycling.

djtrack16 / parens.clj

Created January 13, 2015 02:16

all combos of well-formed parens of size O

	(fn [o]
	(let [f (fn q [s o c]
	(set(remove #(or (coll? %) (nil? %))
	(tree-seq
	coll?
	seq
	(let[j (fn [sep coll] (clojure.string/join sep coll))
	a (if (pos? o) (q (concat s "(") (dec o) (inc c)))
	b (if (pos? c) (q (concat s ")") o (dec c)))]
	(if (and (zero? o) (zero? c))

djtrack16 / gist:d8a24164f702e9f04142

Created January 13, 2015 02:17

all prime factors of n

	(fn primeFactors
	([n] (primeFactors n 2))
	([n div]
	(cond
	(< n div) '()
	(zero? (mod n div)) (cons div (lazy-seq (primeFactors (/ n div) div)))
	:else (recur n (inc div)))))

djtrack16 / rankofPerm.clj

Created January 13, 2015 02:18

given a string and rank, find the permutation is at that index of the sorted permutations

	(fn [s rank]
	(let [n (count s) step (reduce * (range 1 n))]
	(loop [i 0 s (sort s) acc '() r rank step step]
	(let [index (quot r step)]
	(if (= 1 (count s))
	(clojure.string/join (concat acc s))
	(recur (inc i)
	(concat (take index s) (drop (inc index) s))
	(concat acc [(nth s index)])
	(- r (* index step))

djtrack16 / county_name_to_state.yml

Created December 5, 2017 21:09