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(import (chicken io))
(import regex)
(import matchable)
(import (chicken string))
(define in-str
(with-input-from-file "input" read-string))
;; (display in-str)
(define re
"mul\\([0-9]+,[0-9]+\\)|do\\(\\)|don't\\(\\)")
(define matched
(let loop ((start 0) (result '()))
(define search-ret (string-search re in-str start))
(if (not search-ret)
(reverse result)
(loop (cadar (string-search-positions re in-str start))
(cons (car search-ret) result)))))
(define (extract-numbers str)
(define nums-str (substring str 4 (- (string-length str) 1)))
(map string->number (string-split nums-str ",")))
(define (process-instr str)
(cond ((string-search "mul" str) (extract-numbers str))
((string-search "do\\(" str) 'do)
(else 'dont)))
(define (calculate str)
(define vals (extract-numbers str))
(* (car vals) (cadr vals)))
(define sum
(let loop ((is-do #t)
(lst (map process-instr matched))
(ret 0))
(match lst
(() ret)
(('do . r) (loop #t r ret))
(('dont . r) (loop #f r ret))
(((a b) . r) (if is-do
(loop is-do r (+ ret (* a b)))
(loop is-do r ret))))))
(display sum)
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