From 98d37ebf505f1c8299df42eab6495f2dcb4e7ae1 Mon Sep 17 00:00:00 2001 From: Vladan Popovic Date: Thu, 11 Jun 2020 23:11:45 +0200 Subject: [PATCH] A0: Warmup https://www.cs.cornell.edu/courses/cs3110/2020sp/a0/ Time taken to implement ~ 4h 30min. --- warmup.ml | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 warmup.ml diff --git a/warmup.ml b/warmup.ml new file mode 100644 index 0000000..c535b1c --- /dev/null +++ b/warmup.ml @@ -0,0 +1,47 @@ +(* requires: y >= 0 *) +(* requires: d >= 0 *) +let valid_date (y: int) (m: string) (d: int) = + if y < 0 || d < 0 then false + else match m with + | "Jan" | "Mar" | "May" | "Jul" | "Aug" | "Oct" | "Dec" -> d < 32 + | "Feb" -> if (y mod 4 == 0) && (y mod 100 <> 0) then d < 30 else d < 29 + | "Apr" | "Jun" | "Sep" | "Nov" -> d < 31 + | _ -> false + +(* Test leap day in a non-century leap year. *) +let () = assert (valid_date 2020 "Feb" 29) +(* Test invalid day. *) +let () = assert (not (valid_date 2010 "Jun" 50)) + + +(* requires: n > 0 *) +let syr n = + let rec collatz n res = + if n == 1 then res + else if n mod 2 == 0 then collatz (n/2) (res+1) + else collatz ((n*3)+1) (res+1) in collatz n 0 + +(* Test syr *) +let () = assert (syr 1 = 0) +let () = assert (syr 2 = 1) +let () = assert (syr 10 = 6) +let () = assert (syr 3 = 7) + + +let rec next_nacci n l sum = + if n = 0 then sum + else match l with + | [] -> next_nacci (n - 1) [] sum + | h :: t -> next_nacci (n - 1) t (sum + h) + +let nacci n k = + let rec tail_nacci n k res = + if k = 0 then res + else tail_nacci n (k - 1) ((next_nacci n res 0) :: res) + in if k = 1 || k = 0 then [1] else List.rev (tail_nacci n (k - 2) [1; 1]) + + +let () = assert (nacci 2 6 = [1; 1; 2; 3; 5; 8]) +let () = assert (nacci 4 9 = [1; 1; 2; 4; 8; 15; 29; 56; 108]) +let () = assert (nacci 5 9 = [1; 1; 2; 4; 8; 16; 31; 61; 120]) +let () = assert (nacci 7 9 = [1; 1; 2; 4; 8; 16; 32; 64; 127])