RosettaCodeData/Task/Binary-search/Common-Lisp/binary-search-1.lisp

15 lines
374 B
Common Lisp

(defun binary-search (value array)
(let ((low 0)
(high (1- (length array))))
(do () ((< high low) nil)
(let ((middle (floor (+ low high) 2)))
(cond ((> (aref array middle) value)
(setf high (1- middle)))
((< (aref array middle) value)
(setf low (1+ middle)))
(t (return middle)))))))