Mmm, this problem description should be clearer like:

"Initially, there is a Robot at position (0, 0). Given a sequence of its moves, judge if this robot makes a circle, which means *after doing all moves*, it moves back to the original place."

I got rejected for the case of 'DURDLDRRLL'.

In the step 2 of 'U', the robot moves back to the original (0, 0) position. If we judged a circle move at the step 2, however we would be rejected because in fact the problem only cares about the final position of that robot.

Not saying this is a bad problem but it should be clear on the description. Consider an extreme case of 'URDLURDLURDLURDLURDLURDLURDLURDLL'. That robot would be like *circling* all the way before the last 'L' move.