### Add 1 to the middle element of a list

Posted:

**Fri Nov 09, 2018 10:12 am**Hi. Can I please get some help?

"Write a function MID-ADD1 that adds 1 to the middle element of a

three-element list.

For example, (MID-ADD1 ’(TAKE 2

COOKIES)) should return the list (TAKE 3 COOKIES). Note: You

are not allowed to make MID-ADD1 a function of three inputs. It

has to take a single input that is a list of three elements."

Here's what I came up with:

(defun mid-add1 (l) (+ 1 (car (cdr l))))

This only returns the modified element. How can I get the modified list?

"Write a function MID-ADD1 that adds 1 to the middle element of a

three-element list.

For example, (MID-ADD1 ’(TAKE 2

COOKIES)) should return the list (TAKE 3 COOKIES). Note: You

are not allowed to make MID-ADD1 a function of three inputs. It

has to take a single input that is a list of three elements."

Here's what I came up with:

(defun mid-add1 (l) (+ 1 (car (cdr l))))

This only returns the modified element. How can I get the modified list?