Advent of Code 2023, day 1

aoc2023-day1.clj

;; Didn't know yet that there is a special syntax to make regexes overlapping. Got angry and wrote this.

(require '[clojure.string :as str])

(def digits (->> ["one" "two" "three" "four" "five" "six" "seven" "eight" "nine"]
                 (map-indexed (fn [i w] [w (str (inc i))]))
                 (into {})))

(def rx (re-pattern (str/join "|" (conj (keys digits) "[0-9]"))))
(def rx-rev (re-pattern (str/join "|" (conj (map str/reverse (keys digits)) "[0-9]"))))

(defn extract-calibration [l]
  (let [left (#(or (digits %) %) (re-find rx l))
        right (#(or (digits %) %) (str/reverse (re-find rx-rev (str/reverse l))))]
    (parse-long (str left right))))

(->> (slurp "day1.txt")
     str/split-lines
     (mapv extract-calibration)
     (reduce +))