(declaim (optimize (speed 3) (safety 0) (debug 0))) (defconstant +loop-count+ 1000000) (defconstant +expected-checksum+ 4600001) (defparameter +words+ #("alpha" "omega" "delta" "omega" "sigma")) (declaim (ftype (function () fixnum) configured-loop-count)) (defun configured-loop-count () (handler-case (let ((line (read-line *standard-input* nil nil))) (if line (let ((value (parse-integer line :junk-allowed t))) (if (> value 0) value +loop-count+)) +loop-count+)) (error () +loop-count+))) (declaim (ftype (function () string) configured-target)) (defun configured-target () (or (second sb-ext:*posix-argv*) "omega")) (declaim (ftype (function (fixnum string) fixnum) string-eq-loop)) (defun string-eq-loop (limit target) (declare (type fixnum limit) (type string target)) (loop with i of-type fixnum = 0 with acc of-type fixnum = 1 while (< i limit) do (let* ((current (svref +words+ (rem i 5))) (next (if (string= current target) (+ acc 7) (+ acc 3))) (bounded (if (> next 1000000000) (- next 1000000000) next))) (declare (type string current) (type fixnum next bounded)) (setf acc bounded i (+ i 1))) finally (return acc))) (let ((result (string-eq-loop (configured-loop-count) (configured-target)))) (format t "~D~%" result) (sb-ext:exit :code (if (= result +expected-checksum+) 0 1)))