2015-Day12.rkt

#lang racket
(require json)
(require threading)

(define (get-input)
  (file->string "day12.txt"))

(define (input->hash)
  (with-input-from-file "day12.txt"
    (lambda () (read-json))))

(define (string-extract-numbers str)
  (~>> str
       (regexp-match* #px"(-?\\d+)")
       (map string->number)))

(define (part1)
  (~>>
   (get-input)
   (string-extract-numbers)
   (foldl + 0)))

(define (hash-has-value? hsh str)
  (define (value-rec hsh str idx)
    (if (eq? idx #f)
        #f
        (if (and (string? (hash-iterate-value hsh idx)) (equal? (hash-iterate-value hsh idx) str))
            #t
            (value-rec hsh str (hash-iterate-next hsh idx)))))
  (value-rec hsh str (hash-iterate-first hsh)))

(define (hash-numbers-ignore hsh str)
  (define (read-list lst str)
    (define (lst-rec lst str res)
      (cond
        [(empty? lst) res]
        [(number? (car lst)) (lst-rec (cdr lst) str (cons (car lst) res))]
        [(hash? (car lst)) (lst-rec (cdr lst) str (append (read-hash (car lst) str empty) res))]
        [(list? (car lst)) (lst-rec (cdr lst) str (append (read-list (car lst) str) res))]
        [else (lst-rec (cdr lst) str res)]))
    (lst-rec lst str empty))

  (define (search hsh str res idx)
    (cond
      [(eq? idx #f)
       res]
      [(hash? (hash-iterate-value hsh idx))
       (search hsh str (append (read-hash (hash-iterate-value hsh idx) str empty) res) (hash-iterate-next hsh idx))]
      [(list? (hash-iterate-value hsh idx))
       (search hsh str (append (read-list (hash-iterate-value hsh idx) str) res) (hash-iterate-next hsh idx))]
      [(number? (hash-iterate-value hsh idx))
       (search hsh str (cons (hash-iterate-value hsh idx) res) (hash-iterate-next hsh idx))]
      [else
       (search hsh str res (hash-iterate-next hsh idx))]))

  (define (read-hash hsh str res)
    (if (hash-has-value? hsh str)
          empty
        (search hsh str res (hash-iterate-first hsh))))

  (read-hash hsh str empty))

(define (part2)
  (~>> (input->hash)
       (hash-numbers-ignore _ "red")
       (foldl + 0)))