commit 18c13061da0c7b642446e64b7dc1a561c3958fc0 parent 58c83f8af7c4abc47f02dc051fd17da85272eb0d Author: Lukas Henkel <lh@entf.net> Date: Sat, 7 Dec 2024 07:24:51 +0100 Optimize Diffstat:
| M | src/day-7.lisp | | | 25 | ++++++++++++++++--------- |
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/src/day-7.lisp b/src/day-7.lisp @@ -6,9 +6,14 @@ (defparameter *operators-task-1* '(+ *)) (defparameter *operators-task-2* '(+ * combine)) -(defun map-operation-combinations (function length operators) - (apply #'map-product function (loop for n from 1 below length - collect operators))) +(defun map-operator-combinations (function length operators) + (labels ((%map (current n) + (if (= n length) + (funcall function current) + (loop with nn = (1+ n) + for operator in operators + do (%map (cons operator current) nn))))) + (%map nil 0))) (defun number-digits (number) (if (zerop number) @@ -18,19 +23,21 @@ (defun combine (num-1 num-2) (+ (* num-1 (expt 10 (number-digits num-2))) num-2)) -(defun calculate (operators numbers) +(defun calculate (operators numbers test-value) (loop with current = (car numbers) for operator in operators for next in (cdr numbers) do (setf current (funcall operator current next)) + when (> current test-value) + do (return current) finally (return current))) (defun test-value-valid-p (test-value numbers operators) - (map-operation-combinations (lambda (&rest operators) - (when (= test-value (calculate operators numbers)) - (return-from test-value-valid-p t))) - (length numbers) - operators) + (map-operator-combinations (lambda (operators) + (when (= test-value (calculate operators numbers test-value)) + (return-from test-value-valid-p t))) + (1- (length numbers)) + operators) nil) (defun day-7 (input)