# Lasers : Introduction (Level 1)

Lasers is a new type of puzzle I created. (Taken help from this example, The Lazy Laser Physicist: Part 2)
There will more ideas to come too, and they will be a bit simple yet different.

Rules :

• There will be lasers which are shaped like an arrow. The arrows pointing in the respective direction shows where the laser goes and the colour shows the colour which it gives out (for simplicity in this case only one colour will be there).
• There will be boxes which are respectively coloured and these boxes need to get touched by the lasers in order to find a solution.
• The solution however, will not be given as usual. In order to find the solution, you can make a move by rotating the lasers 90° clockwise. For example, the given picture below can occur in 3 moves. • In future levels, there will be grey tiles which block the path of the laser. Lasers itself and the boxes also block the path of other lasers.
• Each box should receive the light of one single laser. In future levels a box may receive the light of 2 or more lasers.

Here is a valid solution, and an invalid one. (1st one is valid, 2nd one is not.) Here is my real puzzle, can you solve it in the least number of moves possible? (Level 1) Note : There are many solutions to this, find the solution with the least number of moves. For now, each move consists of a laser being rotated 90° in clockwise direction.

• Please, don't confuse logic-grid with grid-deduction. Also, if it has multiple solutions AND you need to minimize the moves, it isn't even a grid deduction, rather it's just a game with optimization. (Does board-games or pencil-and-paper-games apply here?) – Bubbler Nov 6 '20 at 6:13
• Also it can be solved in 6 moves in at least three ways, and I'm pretty sure it can't be solved in 5 moves or fewer. That doesn't even make a good optimization. – Bubbler Nov 6 '20 at 6:16
• Not having a unique optimal solution is not an issue for an optimization problem. The real issue is probably that if there are too many optimal solutions, then the puzzle might become trivial. Given that this puzzle is an introduction, I think this is still acceptable. Just make sure to bring us some better-designed (i.e. more challenging) levels! – WhatsUp Nov 6 '20 at 6:37

## 1 Answer

From left to right top to bottom:

R1C7 arrow 2 rotations, R3C4 arrow 1rot, R5C5 arrow 1 rot, R7C1 arrow 2 rot.

Explanation :

First of all the arrow at R1C1 can only be in its position to solve the puzzle. So it should not move.

Now the red square at R3C1 can only be pointed at by arrow R7C1 for optimum. So that requires two moves. Because if it did not move then R3C4 two rots has to be done, R7C7 two rots has to be done leaving 3 squares for 2 lasers, so the puzzle cannot be solved. If it moves 3 times to hit the square at R7C4 then R3C4 two rots, R5C5 1 rot, R1C7 2 rots. Which is 8 moves in total.

Now R7C4 must be covered by either arrow R3C4 or R7C7. If the latter is the case it will take 8 moves minimum to complete the puzzle. R7C7 3 rots, R5C5 2 rots and R1C7 3 rots.

The other option only option is 4 moves R3C4 arrow 1rot, R5C5 arrow 1 rot, R7C1 arrow 2 rot. This means only this configuration is optimal (excluding the fact changing the ordering creates a new solution).

• It would be helpful if you use RnCn notation or similar, or include an image of the result. – Bubbler Nov 6 '20 at 6:23
• Sorry what is rncn notation? – Prince Deepthinker Nov 6 '20 at 6:24
• Row and column numbers, like the first arrow is at R1C1, second is at R1C7, and so on. – Bubbler Nov 6 '20 at 6:25