This isn't really a code, but this tip will help you defeat the rancor. Bide your time by dodging the rancor's grip. Gammoreans will help distract the rancor, if they're behind the rancor's back. When you find some rocks, roll past him ( down + a), and roll under again when the rancor's near the door that kept him trapped. Use force push ( r + b) on the rocks, then when the rancor is right below the door, force push again, then the rock will hit the switch to the door, killing the rancor.