Preventing circles in dungeon generation?

I've been working on a script the last couple of days, that generates a random dungeon as you walk through it. My current problem is that I cant prevent the tiles from forming a circle and ending the maze. I made a tower tile that takes the dungeon up or down a level, so I was thinking that if I can get the tiles to detect when its about to intersect with another one it can replace the next tile with a tower tile. My problem is that I am having trouble getting it to detect this.

Here I have it make the room and push it into an array.

         var newRoom : Transform = (Instantiate(wallArray[Random.Range(1,5)], transform.position, transform.rotation));
         newRoom.transform.position.z = transform.position.z -= 3;
     
         var newDoorFrame : Transform = (Instantiate(wallDoorFrame, transform.position, transform.rotation));
         newDoorFrame.transform.position.z = transform.position.z -= 3;
     
         var newDoor : Transform = (Instantiate(wallArray[6],newDoorFrame.transform.position, newDoorFrame.transform.rotation));
     
         oldRoomPos =  newRoom.position;
         spawnArray.push(newRoom);

I was thinking that I could use the array to somehow tell it when it needs to change based on the last few tiles that were generated. Like if the array was (LeftCorner,Hall,LeftCorner,LeftCorner) it would make the next tile a tower. Thanks in advance, Tracey PS: I can post all the code, but its pretty lengthy.