Data commit

Task/Modular-inverse/OCaml/modular-inverse-1.ocaml

@@ -0,0 +1,8 @@
+let mul_inv a = function 1 -> 1 | b ->
+  let rec aux a b x0 x1 =
+    if a <= 1 then x1 else
+    if b = 0 then failwith "mul_inv" else
+    aux b (a mod b) (x1 - (a / b) * x0) x0
+  in
+  let x = aux a b 0 1 in
+  if x < 0 then x + b else x

Task/Modular-inverse/OCaml/modular-inverse-2.ocaml

@@ -0,0 +1,11 @@
+let rec gcd_ext a = function
+  | 0 -> (1, 0, a)
+  | b ->
+      let s, t, g = gcd_ext b (a mod b) in
+      (t, s - (a / b) * t, g)
+
+let mod_inv a m =
+  let mk_pos x = if x < 0 then x + m else x in
+  match gcd_ext a m with
+  | i, _, 1 -> mk_pos i
+  | _ -> failwith "mod_inv"