Extract a given number of randomly selected elements from a list

	;; P23 (**) Extract a given number of randomly selected elements from a list.
	;; The selected items shall be returned in a list.
	;; Example:
	;; * (rnd-select '(a b c d e f g h) 3)
	;; (E D A)
	;; Hint: Use the built-in random number generator and the result of problem P20.
	#lang racket
	(provide rnd-select)
	(require "p03.ss")
	(require "p20.ss")
	(define (rnd-select lst num)
	(let loop ((lst lst) (selected 0) (acc '()))
	(if (= num selected)
	(reverse acc)
	(let ((rand-pos (+ (random (length lst)) 1)))
	(loop (remove-at lst rand-pos)
	(+ selected 1)
	(cons (element-at lst rand-pos) acc))))))

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