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#lang racket
(define fp (open-input-file "input"))
(define (get-lines fp)
(let loop ((lines '()))
(define l (read-line fp))
(if (eof-object? l)
(reverse lines)
(loop (cons l lines)))))
(define lines (get-lines fp))
(define (extract-game line)
(define game-str (cadr (string-split line ":")))
(define sets-str (string-split game-str ";"))
(set! sets-str (map string-trim sets-str))
(map extract-set sets-str))
(define (extract-set str)
(define r 0)
(define g 0)
(define b 0)
(define balls (string-split str ","))
(set! balls
(map (lambda (s)
(define pair (map string-trim (string-split s " ")))
(list (string->number (car pair)) (cadr pair)))
balls))
(let loop ((balls balls))
(if (null? balls)
'()
(let ()
(define ball (car balls))
(define number (car ball))
(define color (cadr ball))
(cond ((string=? "red" color) (set! r number))
((string=? "green" color) (set! g number))
((string=? "blue" color) (set! b number)))
(loop (cdr balls)))))
(list r g b))
(define (possible? game)
(if (null? game)
#t
(let ()
(define head (car game))
(if (or (> (car head) 12) ; r
(> (cadr head) 13) ; g
(> (caddr head) 14)) ; b
#f
(possible? (cdr game))))))
(define (enumerate lst)
(let loop ((i 1) (ret '()) (remain lst))
(if (null? remain)
(reverse ret)
(loop (+ 1 i) (cons (list (car remain) i) ret) (cdr remain)))))
(apply + (map cadr
(filter (lambda (game)
(possible? (car game)))
(enumerate (map extract-game lines)))))
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