12 lines
359 B
Racket
12 lines
359 B
Racket
#lang typed/racket
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(: collatz (-> Nonnegative-Integer (Listof Nonnegative-Integer)))
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(define (collatz x)
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(cond
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((equal? x 1) (list 1))
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((even? x) (cons x (collatz (quotient x 2))))
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((odd? x) (cons x (collatz (+ 1 (* 3 x)))))
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(else (list))))
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(argmax (λ ((x : Nonnegative-Integer)) (length (collatz x))) (range 1 1000000))
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