More practice for Project 1 in CIS352

p1-more-practice.rkt

#lang racket
(provide (all-defined-out))
;;
;; CIS352 (Fall '24) Racket Warmup
;;

(define (square x) (* x x))

;; return the Euclidian distance between x0,y0 and x1,y1
(define (euclid-distance x0 y0 x1 y1)
  (sqrt (+ (expt (- y1 y0) 2) (expt (- x1 x0) 2))))

;; return #t iff the list l contains a number less than i
(define (contains-less-than l i)
  (match l
    ['() #f]
    [`(,hd . ,tl) #:when (< hd i) #t]
    [`(,hd . ,tl) (contains-less-than tl i)]))

;; valid "shapes" are (a) either rectangles with a lower-left x0/y0
;; and upper-right x1/y1, (b) circles with some center x/y and radius
;; y.
(define (shape? s)
  (match s
    [`(circle ,x-enter ,y-center ,radius) #t]
    [`(rect ,x0 ,y0 ,x1 ,y1) (and (< x0 x1) (< y0 y1))]
    [_ #f]))

;; Calculate the area of a shape.
(define (shape-area s)
  (match s
    ;; hint: use pi
    [`(circle ,x-center ,y-center ,radius) (* pi radius radius)]
    [`(rect ,x0 ,y0 ,x1 ,y1) (abs (* (- y1 y0) (- x1 x0)))]))

;; generate n spaces
(define (spaces n) (make-string n #\space))

;; Assume `l` is a list of cons cells (pairs) whose first element is a
;; column position (natural number) and whose right element is a
;; character to be rendered at that line. You will return a string
;; representing the line.
;;
;; Example:
;;    (draw-ascii-line '((3 . #\=) (4 . #\=) (5 . #\=) (7 . #\.)
;;                       (9 . #\=) (10 . #\=) (11 . #\=)))
;; > "   === . ==="
(define (draw-ascii-line l)
  (define (h l cur-pos)
    (if (empty? l)
      ""
      ;; else
      (let ([next-index (car (first l))]
            [next-char  (cdr (first l))]
            [rest-list  (rest l)])
        (string-append (spaces (- next-index cur-pos))
                       (make-string 1 next-char)
                       (h rest-list (add1 next-index))))))
  ;; sort ascending, comparing only the column position by specifying
  ;; a comparison operator.
   (h (sort l (lambda (x y) (< (car x) (car y)))) 0))