Question

Write a recursive scheme function EXP-DEPTH that returns the depth of the most nested parentheses in a list. (EXP-DEPTH ’A) is 0, (EXP-DEPTH ’( )) is 1, (EXP-DEPTH ’(1 2 3) ) should return 1. (EXP-DEPTH ’(I J ((K) L) M)) should return 3, since the element K is nested in three levels of parentheses.

Please use scheme function

Answer 1

(define (EXP-DEPTH lst)

(If (not (pair? lst))

0

(max (add1 (EXP-DEPTH (car lst)))

(EXP-DEPTH (cdr lst)))))

The trick is using max to find out which branch of the recursion is the deepest, notching that each time we recur on the car we add one more level.

Here lst is LST in lower case

Another method

(define (EXP-DEPTH lst)

(cond ((null?lst ) 0)

((atom ? lst )0)

(else (max(+1(EXP-DEPTH (car lst)))

(EXP-DEPTH (cdr lst))))))