60 lines
2.1 KiB
Common Lisp
60 lines
2.1 KiB
Common Lisp
(load "util.lisp")
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(defparameter input (uiop:read-file-string "3-input"))
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(defun is-good-mul (str)
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(let ((start (search "(" str))
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(middle (search "," str))
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(end (search ")" str)))
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(and (not (null start)) (not (null middle)) (not (null end))
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;; mul( <- 3 character
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(eq start 3)
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;; Simple to understand
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(< start end)
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(< start middle)
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(< middle end)
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;; Make sure the arguments are purely numbers
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(every #'digit-char-p (subseq str (1+ start) middle))
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(every #'digit-char-p (subseq str (1+ middle) end)))))
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(defun parse-mul (str)
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(let ((start (search "(" str))
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(middle (search "," str))
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(end (search ")" str)))
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(list (parse-integer (subseq str (1+ start) middle))
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(parse-integer (subseq str (1+ middle) end)))))
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(defun parse-input-muls (line)
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(let ((possible (search-all "mul" line)))
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(--> (cdr possible)
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(append _ (list (length line)))
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;; index of mul -> (position substring)
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(mapcar (lambda (z1 z2) (cons z1 (subseq line z1 z2))) possible _)
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;; remove any bad muls
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(remove-if-not (lambda (x) (is-good-mul (cdr x))) _)
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;; parse muls
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(mapcar (lambda (x) (cons (car x) (parse-mul (cdr x)))) _))))
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(format t "Round 1: ~a~%"
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(loop for (pos x y) in (parse-input-muls input)
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sum (* x y)))
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(defun parse-input-conds (input)
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(let ((dos (search-all "do()" input))
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(donts (search-all "don't()" input)))
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(--> (append (mapcar (lambda (x) (cons 'do x)) dos)
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(mapcar (lambda (x) (cons 'dont x)) donts))
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(sort _ (lambda (x y) (< (cdr x) (cdr y))))
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(cons '(do . 0) _))))
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(defun current-cond (pos conds)
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(caar (last (remove-if (lambda (x) (> (cdr x) pos)) conds))))
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(format t "Round 2: ~a~%"
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(let ((conds (parse-input-conds input))
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(muls (parse-input-muls input)))
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(loop for (pos x y) in muls
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for current = (current-cond pos conds)
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if (eq current 'do)
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sum (* x y))))
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