This puzzle is a part of the Puzzling Stack Exchange Advent Calendar 2022. The accepted reply to this query will probably be awarded a bounty value 100 repute.
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The 12 months is 1977. Your household is just a little bit behind, so though it is only one week till Christmas, you are lastly getting round to establishing the tree. Your dad is doing a lot of the work, and he is already gotten the tree up and the entire ornaments on it, however now you have discovered him rummaging round in an outdated desk drawer, wanting via all types of items of paper you do not perceive.
“I can not discover the lighting diagram for the tree,” he defined. “I deliberate out the lights and ornaments in a specific manner in order that the entire tree can be lit up, and I discovered the plan for the ornaments, however I can not discover the one for the lights!”
“Can I assist?” you ask, not understanding the place you’d search for the diagram, however your dad says, “Don’t fear,” and leads you again out into the household room.
“I knew this could occur, so I made positive to have a backup. Based on how the ornaments are arrange, you must be capable of determine the place to place all these lights in an effort to mild up the entire tree. Remember what you discovered in physics class – mild can solely journey horizontally and vertically.”
“Dad, I have not taken physics but!” you reply, confused. “I’m solely 9 years outdated!”
Ignoring you, he continues. “And, if you happen to do, you would possibly even be capable of get a touch as to what’s in that huge current we obtained you. As the youngsters say, it is extraordinarily lit – possibly even too lit.”
“Dad, children will not say ‘lit’ for one more 40 years! How am I speculated to determine any of this out?”
“I think about you. I’m gonna go run to the comfort retailer to seize some cigarettes. Good luck – and remember the star on the prime!” And laying a finger apart of his nostril, he hopped into his Oldsmobile and sped off.
I assume you are by yourself now. Can you mild up the tree earlier than your dad comes dwelling, and extra importantly, can you discover out what your Christmas current is?
For a simplified model of the above grid, click on right here.
