Google Code Jam 2014 Qualification

A.rkt

#lang racket
(define (get-candidates)
  (define row (sub1 (read)))
  (for/seteqv ((i (in-range 16))
               (item (in-producer read))
               #:when (= (quotient i 4) row))
    item))

(define T (read))
(for ((c (in-range T)))
  (define cand (set-intersect (get-candidates) (get-candidates)))
  (printf "Case #~a: ~a~%" (add1 c)
          (cond ((set-empty? cand) "Volunteer cheated!")
                ((set-empty? (set-rest cand)) (set-first cand))
                (else "Bad magician!"))))

B.rkt

#lang racket
(define T (read))
(for ((c (in-range T)))
  (define-values (C F X) (values (read) (read) (read)))
  (let loop ((rate 2.0)
             (penalty 0.0)
             (last (/ X 2.0)))
    (define nextrate (+ rate F))
    (define nextpen (+ penalty (/ C rate)))
    (define next (+ (/ X nextrate) nextpen))
    (if (< last next)
        (printf "Case #~a: ~a~%" (add1 c) last)
        (loop nextrate nextpen next))))