Advent of Code: 3

advent-3.clj

(ns advent.a3
  (:require [clojure.string :as str]))

(let [a3 (str//trim (slurp "a3.txt"))]
  (count
   (loop [cs (seq a3) p [0 0] ps #{[0 0]}]
     (if-not (seq cs) ps
             (let [c (first cs)
                   [x y] p
                   next (condp = c
                          \> [(inc x) y]
                          \< [(dec x) y]
                          \^ [x (inc y)]
                          \v [x (dec y)])]
               (recur (rest cs) next (conj ps next)))))))

(let [a3 (str/trim (slurp "a3.txt"))]
  (count
   (loop [cs (seq a3) p [[0 0] [0 0]] ps #{[0 0]}]
     (if-not (seq cs) ps
             (let [c (first cs)
                   [mover waiter] p
                   [x y] mover
                   next (condp = c
                          \> [(inc x) y]
                          \< [(dec x) y]
                          \^ [x (inc y)]
                          \v [x (dec y)])]
               (recur (rest cs) [waiter next] (conj ps next)))))))