Just another update

Task/Longest-string-challenge/Ada/longest-string-challenge-1.ada

@@ -6,20 +6,28 @@ procedure Longest_String_Challenge is
    Separator: constant Character := Ada.Characters.Latin_1.NUL;
 
    procedure Funny_Stuff(B, L: in out Unbounded_String; N: Unbounded_String) is
+      -- B holds a list of all longest strings, separated by Separator
+      -- L holds longest string so far
+      -- N is the next string to be considered
       Nat: Natural;
    begin
       Nat := Length(N) - Length(L);
+        -- (1) this raises exception if L longer then N
       declare
          Pos: Positive;
       begin
-         Pos := Nat;
+         Pos := Nat; -- (2) this raises exception if L at least as long as N
+                     -- at this point, we know N is longer then L
          B   := N;
          L   := N;
       exception
-         when Constraint_Error => B := B & Separator & N;
+         when Constraint_Error -- come from (2)
+            -- at this point, we know L and N are of the same length
+            => B := B & Separator & N; -- add N to the set of solutions
       end;
    exception
-      when Constraint_Error => null;
+      when Constraint_Error => null; -- come from (1)
+        -- at this point, we know L is longer then N
    end Funny_Stuff;
 
    Buffer: Unbounded_String := +"";
@@ -29,10 +37,11 @@ procedure Longest_String_Challenge is
 begin
    while True loop
       Next := + Ada.Text_IO.Get_Line;
+        -- (3) raises exception when trying to read beyond the end of file
       Funny_Stuff(Buffer, Longest, Next);
    end loop;
 exception
-   when others =>
+   when others => -- come from (3)
       for I in To_String(Buffer)'Range loop
          if To_String(Buffer)(I) = Separator then
             Ada.Text_IO.New_Line;

Task/Longest-string-challenge/Ada/longest-string-challenge-2.ada

@@ -11,21 +11,26 @@ procedure Longest_String_Challenge is
                          S, T: String) is
       C: Character;
    begin
-      if S = T then
-         B := B & Separator & N;
-      else
-         C:= T(T'First); -- raises Constraint_Error if T is empty
-         begin
-            C := S(S'First); -- same if S is empty
-            Funny_Stuff(B,L,N,S(S'First+1 .. S'Last), T(T'First+1..T'Last)); --
-         exception
-            when Constraint_Error =>
-               B   := N;
-               L   := N;
-         end;
-      end if;
+      C:= T(T'First); -- (1) raises Constraint_Error if T is empty
+      begin
+	 C := S(S'First); -- (2) raises Constraint_Error if S is empty
+	   -- at this point, we know that neither S nor T are empty
+         Funny_Stuff(B,L,N,S(S'First+1 .. S'Last), T(T'First+1..T'Last));
+      exception
+         when Constraint_Error => -- come from (2), S is empty, T is not empty!
+	    B   := N;
+	    L   := N;
+      end;
    exception
-      when Constraint_Error => null;
+      when Constraint_Error => -- come from (1), T is empty
+	 begin
+	    C := S(S'First); -- (3) raises Constraint_Error if S is empty
+	    -- at this point, we know that T is empty and S isn't
+	    null;
+	exception
+	    when Constraint_Error => -- come from (3); both S and T are empty
+	    B := B & Separator & N;
+	end;
    end Funny_Stuff;
 
    Buffer: Unbounded_String := +"";
@@ -35,10 +40,11 @@ procedure Longest_String_Challenge is
 begin
    while True loop
       Next := + Ada.Text_IO.Get_Line;
+        -- (4) raises exception when trying to read beyond end of file
       Funny_Stuff(Buffer, Longest, Next, -Longest, -Next);
    end loop;
 exception
-   when others =>
+   when others => -- come from (4)
       for I in To_String(Buffer)'Range loop
          if To_String(Buffer)(I) = Separator then
             Ada.Text_IO.New_Line;

Task/Longest-string-challenge/Java/longest-string-challenge.java

@@ -0,0 +1,28 @@
+import java.io.File;
+import java.util.Scanner;
+
+public class LongestStringChallenge {
+
+    public static void main(String[] args) throws Exception {
+        String lines = "", longest = "";
+        try (Scanner sc = new Scanner(new File("lines.txt"))) {
+            while(sc.hasNext()) {
+                String line = sc.nextLine();
+                if (longer(longest, line))
+                    lines = longest = line;
+                else if (!longer(line, longest))
+                    lines = lines.concat("\n").concat(line);
+            }
+        }
+        System.out.println(lines);
+    }
+
+    static boolean longer(String a, String b) {
+        try {
+            String dummy = a.substring(b.length());
+        } catch (StringIndexOutOfBoundsException e) {
+            return true;
+        }
+        return false;
+    }
+}

Task/Longest-string-challenge/Lua/longest-string-challenge-1.lua

@@ -0,0 +1,26 @@
+function longer(s1, s2)
+    while true do
+        s1 = s1:sub(1, -2)
+        s2 = s2:sub(1, -2)
+        if s1:find('^$') and not s2:find('^$') then
+           return false
+        elseif s2:find('^$') then
+           return true
+        end
+    end
+end
+
+local output = ''
+local longest = ''
+
+for line in io.lines() do
+    local islonger = longer(line, longest)
+    if islonger and longer(longest, line) then
+        output = output .. line .. '\n'
+    elseif islonger then
+        longest = line
+        output = line .. '\n'
+    end
+end
+
+print(output)

Task/Longest-string-challenge/Lua/longest-string-challenge-2.lua

@@ -0,0 +1,7 @@
+function longer(s1, s2)
+    if s1:sub(#s2):find('^$') then
+       return false
+    else
+       return true
+    end
+end

Task/Longest-string-challenge/Ruby/longest-string-challenge-2.rb

@@ -0,0 +1 @@
+puts open("test.txt").each_line.group_by(&:size).max.last

Task/Longest-string-challenge/Scala/longest-string-challenge.scala

@@ -0,0 +1,2 @@
+val longest = scala.io.Source.fromFile(args.head).getLines.toIterable.groupBy(_.length).max._2
+println(longest mkString "\n")