flush

flush.rkt

#lang racket/base
 
(require racket/set
         racket/list)
 
(define (P event space)
  (/ (for/fold ([acc 0])
               ([x (in-list space)]
                #:when (event x))
       (add1 acc))
     (length space)))
 
(define (cross A B)
  (for*/list ([a (in-string A)]
              [b (in-string B)])
    (cons a b)))
 
(define suits "SHDC")
(define ranks "A23456789TJQK")
(define deck (cross ranks suits))
(define Hands (combinations deck 5))
 
(define (flush hand)
  (for/or ([suit (in-string suits)])
    (for/and ([card (in-list hand)])
      (equal? suit (cdr card)))))

(time 
 (displayln (P flush Hands)))