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#!/usr/bin/env -S guile -s
!#
(use-modules (ice-9 regex)
(ice-9 textual-ports)
(srfi srfi-1))
(define (read-lines port)
(letrec ((loop (lambda (l ls)
(if (eof-object? l)
ls
(loop (get-line port) (cons l ls))))))
(reverse (loop (get-line port) '()))))
(define (split-up nums)
(filter (lambda (x) (not (string-null? x))) (string-split nums char-set:whitespace)))
(define (score line)
(let* ((m (string-match ": ([0-9| ]+) \\| ([0-9| ]+)" line))
(winning (split-up (match:substring m 1)))
(have (split-up (match:substring m 2)))
(shared (filter (lambda (x) (member x winning)) have)))
(if (null? shared) 0 (expt 2 (- (length shared) 1)))))
(let* ((port (open-input-file "4.txt"))
(lines (read-lines port)))
(close-port port)
(display (fold + 0 (map score lines))))
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