tasks a-s

Task/Reverse-a-string/OCaml/reverse-a-string-1.ocaml

@@ -0,0 +1,9 @@
+let rev_string str =
+  let len = String.length str in
+  let res = String.create len in
+  let last = len - 1 in
+  for i = 0 to last do
+    let j = last - i in
+    res.[i] <- str.[j];
+  done;
+  (res)

Task/Reverse-a-string/OCaml/reverse-a-string-2.ocaml

@@ -0,0 +1,8 @@
+let rev_string str =
+  let last = String.length str - 1 in
+  for i = 0 to last / 2 do
+    let j = last - i in
+    let c = str.[i] in
+    str.[i] <- str.[j];
+    str.[j] <- c;
+  done

Task/Reverse-a-string/OCaml/reverse-a-string-3.ocaml

@@ -0,0 +1,4 @@
+let rec revs strin list index =
+  if List.length list = String.length strin
+  then String.concat "" list
+  else revs strin ((String.sub strin index 1)::list) (index+1)