Non coding challenge: a power story
Since the next coding challenge will be a bit brutal, I thought we all earned a little break so here is a short non coding challenge. I’m pretty sure you won’t find the answer on the net since I just made it up…
Ann was enjoying this Sunday morning in her San Francisco apartment by sipping a nice cup of coffee and browsing the web on her laptop and her home wifi connection when the entire apartment went dark. Her husband entered the room: “I might have tripped a fuse with my computer, I’ll go check the breaker box.” “Don’t bother, it’s a general outage, the neighbors lost power too.” “Oh? How do you know? Did you talk to them?” “No.” “Did you make a phone call or receive one?” “No.” “Did you talk to anyone?” “Only you.” “Did you see something outside that tipped you off?” “No.”
How did Ann know that the outage was general and not just their apartment?
Update 1: I will hold the comments in the moderation queue for a little while to avoid spoilers, but I’ll publish them all shortly.
Update 2: I posted[the solution.
Comments (23)
When her wifi went down she tried to use the neibours but those where gone too.
Obviously she hacked the power plant :P
Well, I assume her laptop keeps running on the battery, but her wifi router will be down. If she checks for her neighbours wifi's she'll see that all surrounding networks are down as well. Is it this simple?
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The neighbours were listening to loud music which stopped suddenly.
Neighbours were listening to loud music. When the power went out, the music died.
her husband was using the neighbours wifi
she might be on a video chat with several neighbors all of them got disconnected before her
No cell phone signal, which means that the reachable relays are powered down :-)
The really noisy party over the road has stopped :) Although why she needs the lights on on a Sunday morning beats me, she should just open the curtains
There was a announcement on web that there will be a power outage in that area at that time
Her husband told her.
they had two independent electric circuits for lights and electric equipment and she just spotted that both went down. Other option: no wifi networks in the area were available. Or she just wanted to get that geeky husband of hers, to bed, instead of sitting for whole time in front of PC! ;)
I'm going with the wifi option.
She no longer sees neighbor's wifi AP on her laptop.
1. Ann heard several screamings 2. She saw all the other Wifis are gone
The neighbor's wifi solution is not perfect, because maybe all neighbors are careful to not broadcast their IDs. OTOH, Ann is using a laptop (which has a battery), so the fact that the laptop can keep working is a big clue to a solution, but that may be a misleading clue. We have the date information, Sunday morning; maybe Matt is on the right track about neighbor's noise... perhaps Ann lives close to a church that uses electricity for the instruments and amplifiers for their loud gospel-music service. This would also be a good reason to keep all windows and curtains shut in the morning! ;)
I think it's because she was working on a laptop and the laptop went dark too, indicating there was an EMP in the area.
My guess was that a neighbor's loud music cut out right at the moment the power went out. But I guess Ann wouldn't be so relaxed with loud music playing on a Sunday morning; though maybe it was classical music that she could barely hear. Wifi sounds right. Personally, I keep my wireless access points, network gear, and cable modem on a UPS (battery backup). A power outage doesn't necessarily cause the cable service to go out, and I can often continue to use internet when there is a power outage (at least until my UPS batteries run out). But I doubt most people do that.
She was sitting by a window. The neighbor's lights went out too.
The neighbors were playing music, which she could hear through the walls, and it stopped at the same time as her lights went out.
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The Big One (9.0) hit SF. The conversation takes place in open air and the husband is obviously in shock.