binary divisible by 3
Write a function that takes a string of binary numbers, separated by commas. It will look like this:
"1100,101,111,1111"Take that string, parse out the numbers, and return a string, in the same format, that only includes numbers divisible by 3.
The return value for the above string would be:
"1100,1111"| (ns tst.demo.core | |
| (:use demo.core tupelo.core tupelo.test) | |
| (:require [schema.core :as s] | |
| [clojure.string :as str])) | |
| (s/defn divisible-by-3 :- s/Str | |
| [binary-str-all] | |
| (let [binstr-div-by-3? (s/fn [binstr :- s/Str] | |
| (it-> binstr | |
| (Integer/parseInt it 2) | |
| (mod it 3) | |
| (zero? it)))] | |
| (it-> binary-str-all | |
| (str/split it #",") | |
| (keep-if binstr-div-by-3? it) | |
| (str/join "," it)))) | |
| (dotest | |
| (is= (divisible-by-3 "1100,101,111,1111") | |
| "1100,1111")) |
| (defn filter-bin-str-divisible-n | |
| "filter comma separated str represented binary numbers when divisible by n (default 3)" | |
| ([input] (filter-bin-str-divisible-n input 3)) | |
| ([input divisor] | |
| (as-> input $ | |
| (clojure.string/split $ #",") | |
| (filter #(= 0 (mod (Integer/parseInt % 2) divisor)) $) | |
| (clojure.string/join "," $)))) | |
| (filter-bin-str-divisible-n "1100,101,111,1111") | |
| ;; => "1100,1111" | |
| (filter-bin-str-divisible-n "1100,101,111,1111" 5) | |
| ;; => "101,1111" |
| (ns pf-1.core | |
| (:gen-class)) | |
| (def input-string "1100, 101, 111, 1111, 011, 100001, 111110") | |
| (defn input-string-to-tokens | |
| "Convert input like \"1101, 101\" to trimmed tokens of the form '1101'" | |
| [input-string] | |
| (map clojure.string/trim (clojure.string/split input-string #","))) | |
| (defn convert-token-to-binseq | |
| "Convert a token of the form '1101' to a sequence (1 1 0 1)" | |
| [token] | |
| (map | |
| #(- (int %) 48) ;char '1' is 49 when forced to int | |
| (char-array token))) | |
| (defn binseq-to-number | |
| "Convert a sequence like (1 0 0 1) to an integer, it does this by zipping the sequence with the corresponding binary factors and accumulating these factors" | |
| [s] | |
| (reduce | |
| (fn | |
| [acc val] | |
| (if (= 1 (second val)) | |
| (+ acc (first val)) | |
| acc) | |
| ) | |
| 0 | |
| (zipmap | |
| (map #(int (Math/pow 2 %)) (range (count s))) | |
| s))) | |
| (defn do-our-thing | |
| [input-string] | |
| (->> input-string ;"111, 1100, 11" | |
| input-string-to-tokens ;("111" "1100" "11") | |
| (map convert-token-to-binseq) ;((1 1 1) (1 1 0 0) (1 1)) | |
| (filter | |
| #(= 0 (mod (binseq-to-number %) 3))) ;((1 1 0 0) (1 1)) | |
| (map clojure.string/join) ;("1100" "11") | |
| (clojure.string/join ",") ;"1100, 11" | |
| )) | |
| (defn -main | |
| [& args] | |
| (println input-string) | |
| (println (do-our-thing input-string))) |
| (require '[clojure.string :as str]) | |
| (defn bdiv5 [bstr] | |
| (->> (when-not (str/blank? bstr) (str/split bstr #",")) | |
| (map #(Long/parseLong % 2)) | |
| (filter #(zero? (rem % 5))) | |
| (map #(Long/toBinaryString %)) | |
| (str/join ","))) |