Data update

Task/Permutations/OCaml/permutations-1.ml

@@ -0,0 +1,45 @@
+(* Iterative, though loops are implemented as auxiliary recursive functions.
+   Translation of Ada version. *)
+let next_perm p =
+	let n = Array.length p in
+	let i = let rec aux i =
+		if (i < 0) || (p.(i) < p.(i+1)) then i
+		else aux (i - 1) in aux (n - 2) in
+	let rec aux j k = if j < k then
+		let t = p.(j) in
+			p.(j) <- p.(k);
+			p.(k) <- t;
+			aux (j + 1) (k - 1)
+	else () in aux (i + 1) (n - 1);
+	if i < 0 then false else
+		let j = let rec aux j =
+			if p.(j) > p.(i) then j
+			else aux (j + 1) in aux (i + 1) in
+		let t = p.(i) in
+			p.(i) <- p.(j);
+			p.(j) <- t;
+			true;;
+
+let print_perm p =
+	let n = Array.length p in
+	for i = 0 to n - 2 do
+		print_int p.(i);
+		print_string " "
+	done;
+	print_int p.(n - 1);
+	print_newline ();;
+
+let print_all_perm n =
+	let p = Array.init n (function i -> i + 1) in
+	print_perm p;
+	while next_perm p do
+		print_perm p
+	done;;
+
+print_all_perm 3;;
+(* 1 2 3
+   1 3 2
+   2 1 3
+   2 3 1
+   3 1 2
+   3 2 1 *)