48 lines
1.8 KiB
Common Lisp
48 lines
1.8 KiB
Common Lisp
;; https://adventofcode.com/2022/day/13
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;; (defparameter *day13-file-name* "day13-test.txt")
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(defparameter *day13-file-name* "day13-input.txt")
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(defparameter *day13-all-list* nil)
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;; 5739 is too low & incorrect
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;; 6398 too high
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(defun nest-2-< (left right)
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(cond
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((and (numberp left) (numberp right)) (- left right))
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((numberp left) (nest-2-< (list left) right))
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((numberp right) (nest-2-< left (list right)))
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((and (listp left) (listp right))
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(cond
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((and (not left) (not right)) 0) ; both equal and empty
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((not left) -1) ; only left empty, left is smaller
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((not right) 1) ; only right is empty, left is bigger
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(t (if (equal (first left) (first right))
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(nest-2-< (rest left) (rest right))
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(let ((head-comparison (nest-2-< (first left) (first right))))
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(if (= 0 head-comparison)
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(nest-2-< (rest left) (rest right))
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head-comparison))))))
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(t 'default)))
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(progn
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(defparameter *day13-all-list* nil)
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(setq *day13-all-list*
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(with-open-file (in *day13-file-name*)
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(read in)))
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(defparameter *day13-lefts* nil)
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(defparameter *day13-rights* nil)
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(loop for i from 0 below (length *day13-all-list*)
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when (= 0 (mod i 2)) do (push (nth i *day13-all-list*) *day13-lefts*)
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when (= 1 (mod i 2)) do (push (nth i *day13-all-list*) *day13-rights*))
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(setq *day13-lefts* (reverse *day13-lefts*))
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(setq *day13-rights* (reverse *day13-rights*))
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(defparameter *day13-indices* nil)
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(setq *day13-indices* (loop
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for i from 0 below (length *day13-lefts*)
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when (< (nest-2-< (nth i *day13-lefts*) (nth i *day13-rights*)) 0)
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collect (1+ i)))
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(apply #'+ *day13-indices*))
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