Data commit

Task/Longest-common-subsequence/OCaml/longest-common-subsequence-1.ocaml

@@ -0,0 +1,10 @@
+let longest xs ys = if List.length xs > List.length ys then xs else ys
+
+let rec lcs a b = match a, b with
+   [], _
+ | _, []        -> []
+ | x::xs, y::ys ->
+    if x = y then
+      x :: lcs xs ys
+    else
+      longest (lcs a ys) (lcs xs b)

Task/Longest-common-subsequence/OCaml/longest-common-subsequence-2.ocaml

@@ -0,0 +1,20 @@
+let lcs xs ys =
+  let cache = Hashtbl.create 16 in
+  let rec lcs xs ys =
+    try Hashtbl.find cache (xs, ys) with
+    | Not_found ->
+        let result =
+          match xs, ys with
+          | [], _ -> []
+          | _, [] -> []
+          | x :: xs, y :: ys when x = y ->
+              x :: lcs xs ys
+          | _ :: xs_rest, _ :: ys_rest ->
+              let a = lcs xs_rest ys in
+              let b = lcs xs      ys_rest in
+              if (List.length a) > (List.length b) then a else b
+        in
+        Hashtbl.add cache (xs, ys) result;
+        result
+  in
+  lcs xs ys

Task/Longest-common-subsequence/OCaml/longest-common-subsequence-3.ocaml

@@ -0,0 +1,15 @@
+let lcs xs' ys' =
+  let xs = Array.of_list xs'
+  and ys = Array.of_list ys' in
+  let n = Array.length xs
+  and m = Array.length ys in
+  let a = Array.make_matrix (n+1) (m+1) [] in
+  for i = n-1 downto 0 do
+    for j = m-1 downto 0 do
+      a.(i).(j) <- if xs.(i) = ys.(j) then
+                     xs.(i) :: a.(i+1).(j+1)
+                   else
+                     longest a.(i).(j+1) a.(i+1).(j)
+    done
+  done;
+  a.(0).(0)

Task/Longest-common-subsequence/OCaml/longest-common-subsequence-4.ocaml

@@ -0,0 +1,10 @@
+let list_of_string str =
+  let result = ref [] in
+  String.iter (fun x -> result := x :: !result)
+              str;
+  List.rev !result
+
+let string_of_list lst =
+  let result = String.create (List.length lst) in
+  ignore (List.fold_left (fun i x -> result.[i] <- x; i+1) 0 lst);
+  result