AOC 2023 Day 1

day1.clj

(ns cloud.seltzer1717.aoc.day1
  (:import (java.io BufferedReader FileReader)
           (java.util.regex Pattern)))

(defn sumOfCalibration1
  "Takes calibration document, returns sum of calibration lines."
  [docPath]
  (let [firstRegex #"^.*?(?<dgt>\d).*$" ;; reluctant
        lastRegex  #"^.*(?<dgt>\d).*?$" ;; greedy
        rgxNbr     (fn [rgx ln]
                     (let [mtr (.matcher rgx ln)]
                       (.find mtr)
                       (.group mtr "dgt")))]
    (with-open [docReader (BufferedReader. (FileReader. docPath))]
      (loop [line (.readLine docReader)
             sum 0]
        (if line
            (recur
              (.readLine docReader)
              (+ sum (Integer/parseInt (str (rgxNbr firstRegex line) (rgxNbr lastRegex line)))))
            sum)))))

(defn sumOfCalibration2
  "Takes calibration document, returns sum of calibration lines."
  [docPath]
  (let [dgt "(\\d|zero|one|two|three|four|five|six|seven|eight|nine)"
        nbrToDgt {"zero"  "0"
                  "one"   "1"
                  "two"   "2"
                  "three" "3"
                  "four"  "4"
                  "five"  "5"
                  "six"   "6"
                  "seven" "7"
                  "eight" "8"
                  "nine"  "9"}
        firstRegex (Pattern/compile (str "^.*?(?<dgt>" dgt ").*$")) ;; reluctant
        lastRegex  (Pattern/compile (str "^.*(?<dgt>" dgt ").*?$")) ;; greedy
        rgxNbr     (fn [rgx ln]
                     (let [mtr (.matcher rgx ln)]
                       (.find mtr)
                       (let [nbr (.group mtr "dgt")]
                         (get nbrToDgt nbr nbr))))]
    (with-open [docReader (BufferedReader. (FileReader. docPath))]
      (loop [line (.readLine docReader)
             sum 0]
        (if line
            (recur
              (.readLine docReader)
              (+ sum (Integer/parseInt (str (rgxNbr firstRegex line) (rgxNbr lastRegex line)))))
            sum)))))