Adjacent Elements Product

Lisp Adjacent Elements Product

(defun adjacent-elements-product (input-array)
  (let ((vec (coerce input-array 'vector))
        (max-product most-negative-fixnum))
    (dotimes (i (1- (length vec)))
      (setf max-product (max max-product (* (aref vec i) (aref vec (1+ i))))))
    max-product))

This walks through neighboring values, multiplies each pair, and keeps the biggest product it finds.