#lang racket

(require "../lib.rkt")

(define (parse line)
  (match-let ([(list min max char pass)
               (regexp-split #rx"[- ]" (regexp-replace #rx": " line " "))])
    (list (string->number min)
          (string->number max)
          (string-ref char 0)
          (string->list pass))))

(define input (map parse (problem-input 2)))

(define part1
  (length (filter (λ (entry)
                    (match-let* ([(list min max char pass) entry]
                                 [occurrences (length (filter (∂ char=? char) pass))])
                      (<= min occurrences max)))
                  input)))

(define part2
  (length (filter (λ (entry)
                    (match-let* ([(list min max char pass) entry])
                      (xor (char=? (list-ref pass (sub1 min)) char)
                           (char=? (list-ref pass (sub1 max)) char))))
                  input)))

(show-solution part1 part2)