The puzzle above has a robot (marked with an arrow pointing up, or “north”) that you can control with a set of command cards that either move the robot forwards a set number of spaces (the + numbers) or backwards (the – numbers). After using a command card, the card is used up and can’t be used again.
If the robot hits either the border of the grid or one of the black spaces, the robot stops moving and any remaining steps on the command card being used are ignored.
Landing on one of the spaces marked with circles causes your robot to turn 90 degrees. (That is, if the robot faces north it turns east, if east it turns south, if south it turns west, and if west it turns north.) The robot starts facing north. Can you get the robot to the star?
Filed under: Education, Mathematics, Puzzles |
The Number Warrior 
I think I’m missing something. If you it a wall or black box, do you then move forward in the opposite direction?
Hitting a wall or black box does not turn your robot around. So if you’re going forward and you hit a wall or black box (and not on a turning circle) then the only next move possible is one of the backwards cards.
It seemed impossible. I’ll have to keep thinking about it. Did you make this up yourself?
I wrote it, yes. Let me know if you need a hint.
If you’re going backwards, you’re still faced forward, right? So the 90 degree turn, which is always a right turn, becomes in effect a left turn?
Suppose from the start you went +6 and then -1. Then after the turn the robot would be on the circle in the middle facing east.
This seems to work:
+5,-3,+1,-5,+2,+7,+2,+5
It would make make for a fun flash game 🙂
I would guess that there are multiple ways to solve this, and some interesting follow on questions might be:
Can you use all available moves and end up on the star?
What is the least amount of moves needed to end up on the star?
What other starting points/directions enable or not enable you to end up on the star?
btw, this reminded me of http://light-bot.com/
Light Bot looks pretty sweet. I might pick it up. There’s quite a few other precedents, including the board game Robo Rally.
It’s possible to use every card. I’m not 100% sure how many solutions there are total.