scheme

I need to implement a procedure called inverse-tree that receives a tree whose nodes data values are numbers and booleans and returns the equivalent tree whose nodes satisfy the following: If the equivalent node of the original tree is a number, then the resulting tree’s node is −1· that node value If the equivalent node of the original tree is a boolean, then the resulting tree’s node is the logical not of that node value Examples: > (inverse-tree ’()) ’() > (inverse-tree ’(5)) ’(-5) > (inverse-tree ’(0)) ’(0) > (inverse-tree ’(#f)) ’(#t) > (inverse-tree ’(#t)) ’(#f) > (inverse-tree ’(-5 (1 (

I have the function below which converts an input of numbers into the partially translated word output of those numbers. Using product and quotient, it adds the word representation of numbers while splitting the number into groups. For example: (number-name 87969087) -> '(87 million 969 thousand 87) (number-name 1000000) -> '(1 million) Im trying to complete my problem by fully translating those numbers which are less than 1000 as well. Im trying to implement a function less-than-1000 which will display those smaller numbers as the list is being constructed as well. Alongside: ;; for less than

I am trying to remove duplicates in a list, using recursion. This is what I have. It only removes the first duplicate, not all of them. My idea is to look at the first member, check if its a member of the rest of the list, if so, call the function again. If not, create a list with the first member and the result from calling the function again. I don't understand why it doesn't remove all the duplicates. (define (removeDupes L) (cond ((null? L) ()) ((list? (member (car L) (cdr L))) removeDupes (cdr L)) (#T (cons ((car L) (removeDupes (cdr L))))))) This is what I modified it to, and it works!!

i've got a problem: I need to find if list equal to the second one, for example: (set%eq? '(1 2 3) '(1 2 3)) ===> #t (set%eq? '(1 2 3) '(2 3 4)) ===> #f That examples are correct in my program, but this one is not: (set%eq? (quote ((quote one) (quote two) (quote three))) (quote ((quote one) (quote two) (quote three)))) ====> #f but i need #t what's wrong? this is my program: (define (set-eq? xs ys) (cond ((and (null? xs) (null? ys)) #t) ((null? ys) #f) ((eq? (car xs) (car ys)) (set-eq? (cdr xs) (cdr ys))) ((eq? (car xs) (car (reverse ys))) (set-eq? (cdr xs) (cdr (reverse ys)))) (else #f)))

I want to show the result of my function as a list not as a number. My result is: (define lst (list )) (define (num->base n b) (if (zero? n) (append lst (list 0)) (append lst (list (+ (* 10 (num->base (quotient n b) b)) (modulo n b)))))) The next error appears: expected: number? given: '(0) argument position: 2nd other arguments...: 10 I think you have to rethink this problem. Appending results to a global variable is definitely not the way to go, let's try a different approach via tail recursion: (define (num->base n b) (let loop ((n n) (acc '())) (if (< n b) (cons n acc) (loop (quotient n b)

I need to write a recursive function in Scheme which takes a list of atoms and reverses it in linear time. I am only allowed to use define, lambda, cons, car, cdr, cond, let, and null? . Here is what I have so far: (define reverse (lambda (lat) (cond ((null? lat) lat) (else (cons (reverse (cdr lat)) (cons (car lat) '())))))) So when I call the function: (reverse '(a b c d)) I get the following output: '(() (((() 4) 3) 2) 1) Any help would be very much appreciated. The problem is that if (reverse (cdr lat)) returns a list eg (3 2) then (cons '(3 2) (1)) turns into ((3 2) 1) . A classical way to

I have a finite list of quadruples, e.g. (list (list 1 3 5 5) (list 2 3 4 9) (list 3 4 4 6)(list 4 7 10 3)). I denote each of the elements by (a1 a2 a3 a4). Please help me to write a sorting function which provides a "increasing" list created according to the following criteria: the numbers a2, later the difference (a3 - a4), and later the numbers a3. Please help if you can. As far as I can tell, your ordered criteria are the order in which to sort. If this is the case, then the following program should perform that sorting. (define (strange-sort quadruples) (define (a2 quad) (cadr quad))

I'm stuck in the middle of my project. I have a list of lists like: '((a for apple) (b is book) (c in cat) (ronn live in NY)) Now I want to make a query in the form of a list and have it display the correct entry in my list of lists. For example, if I input '(a for what) or '(what in cat) it will display (a for apple) or (c in cat) . If I input '(ronn live in where) it will show (ronn live in NY) . Can anyone help me solve this problem? How about running a filter routine across the list, and using a lambda object initialized with your query information that will then be applied to the list