aoc 6

custom_customs.rkt

#lang racket

(define input
  (port->lines (open-input-file "input6.in")))

; for Section 1
; (define (split-groups gs)
;  (let aux [(in gs) (curr-g "") (out `())]
;    (cond
;      [(null? (cdr in)) (cons curr-g out)]
;      [(equal? (car in) "") (aux (cdr in) "" (cons curr-g out))]
;      [else (aux (cdr in) (string-append curr-g (car in)) out)])))

; (define (split-group-into-char-set-len g) (length (remove-duplicates (map string (string->list g)))))

; (define (split-group-into-char-set-len g) (length (remove-duplicates (map string (string->list g)))))

; (apply + (map split-group-into-char-set-len (split-groups input)))

 (define (split-groups gs)
  (let aux [(in gs) (curr-g `()) (out `())]
    (cond
      [(null? (cdr in)) (cons curr-g out)]
      [(equal? (car in) "") (aux (cdr in) `() (cons curr-g out))]
      [else (aux (cdr in) (cons (string->list (car in)) curr-g) out)])))


(define (count-intersect g) (length (group-intersect g)))

(define (group-intersect g)
  (let aux [(in g) (out (car g))]
    (cond
      [(null? (cdr in)) (set-intersect (car in) out)]
      [else (aux (cdr in) (set-intersect (car in) out))])))

(apply + (map count-intersect (split-groups input)))