ホーム - Project Euler

Problem 2¶

#!r6rs
#!chezscheme

(import (chezscheme))

(define answer-2
  (let loop ([first 0] [second 1] [result 0])
    (let ([next (+ first second)])
      (cond
        [(< 4000000 next) result]
        [(even? next)
         (loop second next (+ result next))]
        [else (loop second next result)]))))

(printf "2: ~D~%" answer-2)