Vladan Popovic
98d37ebf50
https://www.cs.cornell.edu/courses/cs3110/2020sp/a0/ Time taken to implement ~ 4h 30min.
47 lines
1.4 KiB
OCaml
47 lines
1.4 KiB
OCaml
(* requires: y >= 0 *)
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(* requires: d >= 0 *)
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let valid_date (y: int) (m: string) (d: int) =
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if y < 0 || d < 0 then false
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else match m with
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| "Jan" | "Mar" | "May" | "Jul" | "Aug" | "Oct" | "Dec" -> d < 32
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| "Feb" -> if (y mod 4 == 0) && (y mod 100 <> 0) then d < 30 else d < 29
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| "Apr" | "Jun" | "Sep" | "Nov" -> d < 31
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| _ -> false
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(* Test leap day in a non-century leap year. *)
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let () = assert (valid_date 2020 "Feb" 29)
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(* Test invalid day. *)
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let () = assert (not (valid_date 2010 "Jun" 50))
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(* requires: n > 0 *)
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let syr n =
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let rec collatz n res =
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if n == 1 then res
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else if n mod 2 == 0 then collatz (n/2) (res+1)
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else collatz ((n*3)+1) (res+1) in collatz n 0
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(* Test syr *)
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let () = assert (syr 1 = 0)
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let () = assert (syr 2 = 1)
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let () = assert (syr 10 = 6)
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let () = assert (syr 3 = 7)
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let rec next_nacci n l sum =
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if n = 0 then sum
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else match l with
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| [] -> next_nacci (n - 1) [] sum
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| h :: t -> next_nacci (n - 1) t (sum + h)
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let nacci n k =
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let rec tail_nacci n k res =
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if k = 0 then res
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else tail_nacci n (k - 1) ((next_nacci n res 0) :: res)
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in if k = 1 || k = 0 then [1] else List.rev (tail_nacci n (k - 2) [1; 1])
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let () = assert (nacci 2 6 = [1; 1; 2; 3; 5; 8])
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let () = assert (nacci 4 9 = [1; 1; 2; 4; 8; 15; 29; 56; 108])
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let () = assert (nacci 5 9 = [1; 1; 2; 4; 8; 16; 31; 61; 120])
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let () = assert (nacci 7 9 = [1; 1; 2; 4; 8; 16; 32; 64; 127])
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