aoc2020/4.rkt

#lang curly-fn racket

(require "scripts/aoc.rkt")

;; solution for day 4

;; helper functions here
(define-simple-macro (magic-struct name:id fld:id ...+)
  #:with fld-names (format-id #'name "~a-fields" #'name)
  (begin (struct name [fld ...] #:transparent)
         (define fld-names (map symbol->string '(fld ...)))))

(magic-struct passport byr iyr eyr hgt hcl ecl pid cid)

(define (string->passport str)
  (define pp (make-vector 8 #f))
  (for ([part (in-list (string-split str))])
    (match-define (list name val) (string-split part ":"))
    (vector-set! pp (index-of passport-fields name) val))
  (apply passport (vector->list pp)))

(define pp-valid-part1?
  (struct/c passport string? string? string? string? string? string? string? any/c))

(define (part1 input)
  (stream-count pp-valid-part1? (in-list input)))

(define (strlen/c num) (compose (=/c num) string-length))
(define (string-integer-in low high) (compose (integer-in low high) string->number))
(define (height/c hs)
  (match hs
    [(pregexp #px"([0-9]+)cm" (list _ h)) ((string-integer-in 150 193) h)]
    [(pregexp #px"([0-9]+)in" (list _ h)) ((string-integer-in 59 76) h)]
    [_ #f]))

(define pp-valid-part2?
  (and/c pp-valid-part1?
         (struct/c passport
                   (and/c (strlen/c 4) (string-integer-in 1920 2002))
                   (and/c (strlen/c 4) (string-integer-in 2010 2020))
                   (and/c (strlen/c 4) (string-integer-in 2020 2030))
                   height/c
                   (curry regexp-match #px"#[0-9a-f]{6}")
                   (or/c "amb" "blu" "brn" "gry" "grn" "hzl" "oth")
                   (and/c (strlen/c 9) (string-integer-in 0 999999999))
                   any/c)))

(define (part2 input)
  (stream-count pp-valid-part2? (in-list input)))

(module+ main
  (define input (map string->passport (string-split (file->string "inputs/4") "\n\n")))

  ;; part 1
  (answer 4 1 (part1 input))

  ;; part 2
  (answer 4 2 (part2 input))

  (displayln "meow"))