solver.clj

;; 1. Unhandled java.lang.IllegalArgumentException
;;    Don't know how to create ISeq from:
;;    doublets.solver$doublets$doublets_rec__3564$fn__3569

;;                        RT.java:  505  clojure.lang.RT/seqFrom
;;                        RT.java:  486  clojure.lang.RT/seq
;;                       core.clj:  133  clojure.core/seq
;;                       core.clj: 2551  clojure.core/map/fn
;;                   LazySeq.java:   40  clojure.lang.LazySeq/sval
;;                   LazySeq.java:   49  clojure.lang.LazySeq/seq
;;                        RT.java:  484  clojure.lang.RT/seq
;;                       core.clj:  133  clojure.core/seq
;;                       core.clj: 2551  clojure.core/map/fn
;;                   LazySeq.java:   40  clojure.lang.LazySeq/sval
;;                   LazySeq.java:   49  clojure.lang.LazySeq/seq
;;                        RT.java:  484  clojure.lang.RT/seq
;;                       core.clj:  133  clojure.core/seq
;;                       core.clj:  624  clojure.core/apply
;;                     solver.clj:   21  doublets.solver/doublets/doublets-rec
;;                     solver.clj:   25  doublets.solver/doublets
;;                           REPL:    1  doublets.solver/eval3577
;;                  Compiler.java: 6703  clojure.lang.Compiler/eval
;;                  Compiler.java: 6666  clojure.lang.Compiler/eval
;;                       core.clj: 2927  clojure.core/eval
;;                       main.clj:  239  clojure.main/repl/read-eval-print/fn
;;                       main.clj:  239  clojure.main/repl/read-eval-print
;;                       main.clj:  257  clojure.main/repl/fn
;;                       main.clj:  257  clojure.main/repl
;;                    RestFn.java: 1096  clojure.lang.RestFn/invoke
;;         interruptible_eval.clj:   56  clojure.tools.nrepl.middleware.interruptible-eval/evaluate/fn
;;                       AFn.java:  152  clojure.lang.AFn/applyToHelper
;;                       AFn.java:  144  clojure.lang.AFn/applyTo
;;                       core.clj:  624  clojure.core/apply
;;                       core.clj: 1862  clojure.core/with-bindings*
;;                    RestFn.java:  425  clojure.lang.RestFn/invoke
;;         interruptible_eval.clj:   41  clojure.tools.nrepl.middleware.interruptible-eval/evaluate
;;         interruptible_eval.clj:  171  clojure.tools.nrepl.middleware.interruptible-eval/interruptible-eval/fn/fn
;;                       core.clj: 2402  clojure.core/comp/fn
;;         interruptible_eval.clj:  138  clojure.tools.nrepl.middleware.interruptible-eval/run-next/fn
;;                       AFn.java:   22  clojure.lang.AFn/run
;;        ThreadPoolExecutor.java: 1145  java.util.concurrent.ThreadPoolExecutor/runWorker
;;        ThreadPoolExecutor.java:  615  java.util.concurrent.ThreadPoolExecutor$Worker/run
;;                    Thread.java:  745  java.lang.Thread/run


(ns doublets.solver
  (:require [clojure.java.io :as io]
            [clojure.edn :as edn]
            [clojure.set :as sets]))

(def words (-> "words.edn"
               (io/resource)
               (slurp)
               (read-string)))

(defn doublets [word1 word2]
  (letfn [(doublets-rec [from visited available to]
            (cond
              (= from to) visited
              (empty? available) []
              :else (let [neighbours (-> available
                                         (map (fn [x] [x (diff from x)]))
                                         (filter #(= (% 0) 1))
                                         (map #(% 1)))]
                      (apply concat
                             (map
                              #(doublets-rec % (conj visited %)
                                             (sets/difference available %) to)
                              neighbours)))))]
    (doublets-rec word1 [] (into #{} words) word2)))

(defn diff [w1 w2]
  "Positionally compares the given collections and returns the number of differing elements."
  (+ (Math/abs (- (count w1) (count w2)))
     (count (filter #(not (= (% 0) (% 1))) (map #(into [] %&) w1 w2)))))