Initial data commit

Task/100-doors/Transact-SQL/100-doors-1.sql

@@ -0,0 +1,40 @@
+WITH    OneToTen (N)
+AS  (   SELECT  N
+        FROM (  VALUES (0), (1), (2), (3), (4), (5), (6), (7), (8), (9)
+                ) V(N)
+        )
+    ,   InitDoors (Num, IsOpen)
+AS  (   SELECT  1
+            +   1 * Units.N
+            +   10 * Tens.N As Num
+            ,   Convert(Bit, 0) As IsOpen
+        FROM    OneToTen As Units
+        CROSS JOIN  OneToTen As Tens
+        ) -- This part could be easier with a tally table or equivalent table-valued function
+    ,   States (NbStep, Num, IsOpen)
+AS  (   SELECT  0 As NbStep
+            ,   Num
+            ,   IsOpen
+        FROM    InitDoors As InitState
+        UNION ALL
+        SELECT  1 + NbStep
+            ,   Num
+            ,   CASE Num % (1 + NbStep)
+                    WHEN 0 THEN ~IsOpen
+                    ELSE IsOpen
+                END
+        FROM    States
+        WHERE   NbStep < 100
+        )
+SELECT  Num As DoorNumber
+    ,   Concat( 'Door number ', Num, ' is '
+            ,   CASE IsOpen
+                    WHEN 1 THEN ' open'
+                    ELSE ' closed'
+                END ) As Result -- Concat needs SQL Server 2012
+FROM    States
+WHERE   NbStep = 100
+ORDER By Num
+; -- Fortunately, maximum recursion is 100 in SQL Server.
+-- For more doors, the MAXRECURSION hint should be used.
+-- More doors would also need an InitDoors with more rows.

Task/100-doors/Transact-SQL/100-doors-2.sql

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+SET NOCOUNT ON;
+
+-- Doors can be open or closed.
+DECLARE @open CHAR(1) = 'O';
+DECLARE @closed CHAR(1) = 'C';
+
+-- There are 100 doors in a row that are all initially closed.
+DECLARE @doorsCount INT = 100;
+DECLARE @doors TABLE (doorKey INT PRIMARY KEY, doorState CHAR(1));
+WITH sample100 AS (
+    SELECT TOP(100) object_id
+    FROM sys.objects
+)
+INSERT @doors
+  SELECT ROW_NUMBER() OVER (ORDER BY A.object_id) AS doorKey,
+    @closed AS doorState
+  FROM sample100 AS A
+      CROSS JOIN sample100 AS B
+      CROSS JOIN sample100 AS C
+      CROSS JOIN sample100 AS D
+  ORDER BY 1
+  OFFSET 0 ROWS
+  FETCH NEXT @doorsCount ROWS ONLY;
+
+-- You make 100 passes by the doors, visiting every door and toggle the door (if
+-- the door is closed, open it; if it is open, close it), according to the rules
+-- of the task.
+DECLARE @pass INT = 1;
+WHILE @pass <= @doorsCount BEGIN
+  UPDATE @doors
+  SET doorState = CASE doorState WHEN @open THEN @closed ELSE @open END
+  WHERE doorKey >= @pass
+    AND doorKey % @pass = 0;
+
+  SET @pass = @pass + 1;
+END;
+
+-- Answer the question: what state are the doors in after the last pass?
+-- The answer as the query result is:
+SELECT doorKey, doorState FROM @doors;
+-- The answer as the console output is:
+DECLARE @log VARCHAR(max);
+DECLARE @doorKey INT = (SELECT MIN(doorKey) FROM @doors);
+WHILE @doorKey <= @doorsCount BEGIN
+  SET @log = (
+      SELECT TOP(1) CONCAT('Doors ', doorKey, ' are ',
+        CASE doorState WHEN @open THEN ' open' ELSE 'closed' END, '.')
+      FROM @doors
+      WHERE doorKey = @doorKey
+    );
+  RAISERROR (@log, 0, 1) WITH NOWAIT;
+
+  SET @doorKey = (SELECT MIN(doorKey) FROM @doors WHERE doorKey > @doorKey);
+END;
+
+-- Which are open, which are closed?
+-- The answer as the query result is:
+SELECT doorKey, doorState FROM @doors WHERE doorState = @open;
+SELECT doorKey, doorState FROM @doors WHERE doorState = @closed;
+-- The answer as the console output is:
+SET @log = (
+  SELECT CONCAT('These are open doors: ',
+    STRING_AGG(CAST(doorKey AS VARCHAR(max)), ', '), '.')
+  FROM @doors
+  WHERE doorState = @open
+);
+RAISERROR (@log, 0, 1) WITH NOWAIT;
+SET @log = (
+  SELECT CONCAT('These are closed doors: ',
+    STRING_AGG(CAST(doorKey AS VARCHAR(max)), ', '), '.')
+  FROM @doors
+  WHERE doorState = @closed
+);
+RAISERROR (@log, 0, 1) WITH NOWAIT;
+
+-- Assert:
+DECLARE @expected TABLE (doorKey INT PRIMARY KEY);
+SET @doorKey = 1;
+WHILE @doorKey * @doorKey <= @doorsCount BEGIN
+  INSERT @expected VALUES (@doorKey * @doorKey);
+  SET @doorKey = @doorKey + 1;
+END;
+IF NOT EXISTS (
+    SELECT doorKey FROM @doors WHERE doorState = @open
+    EXCEPT
+    SELECT doorKey FROM @expected
+  )
+  AND NOT EXISTS (
+    SELECT doorKey FROM @expected
+    EXCEPT
+    SELECT doorKey FROM @doors WHERE doorState = @open
+  )
+  PRINT 'The task is solved.';
+ELSE
+  THROW 50000, 'These aren''t the doors you''re looking for.', 1;