2445
Programmer tries to explain binary search to the police
(startrek.website)
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 30 Nov 2023
2445 points (100.0% liked)
Programmer Humor
25457 readers
1039 users here now
Welcome to Programmer Humor!
This is a place where you can post jokes, memes, humor, etc. related to programming!
For sharing awful code theres also Programming Horror.
Rules
- Keep content in english
- No advertisements
- Posts must be related to programming or programmer topics
founded 2 years ago
MODERATORS
Not with a binary search.
Edit: just collapse this thread and move on. Cosmic Cleric is an obvious troll.
Well now I HAD to read the thread
What an absolute weirdo.
Yes you will.
A binary search is just what it says, it's just for searching only.
When you find that moment in time where the bike was there one moment, and then the next moment the bike's not there, then you view at regular or even slow-mo at those few seconds of the bike in the middle of disappearing, and see the perpetrator, and hopefully can identify them.
You didn't get what was talked about here. Re-read the topmost parent comment.
How do you binary search for two people arriving, one punches the other, they both leave?
I was responding to this ...
I disagree with the "leaves no visual cue" part, as I've commented on. There's ALWAYS something caught on the video to help determine things. Maybe not enough, but never nothing.
Maybe I'm not understanding both arguments here but I'd like to understand. I've had to review footage of a vending machine being shaken to release drinks.
You have no before or after visual clue as to when the event took place. The only indication is when you physically see it happening. The same could be said for an assault. If nothing is changed in the before or after static still how can you pinpoint the incident?
In the same way the OP talks about it ...
Instead of a bike, you look for the aftereffects of a fight happening (chairs knocked down, tables turned over, etc.). You can even look at how many people congregate around the location of the fight before and after the video as a 'marker' to the point of time the fight was happening/just finished.
Edit: One thing we didn't even mention, AI can also be used these days to notice subtle changes in the video. If a video is a static image of an alley, then two people walk in the alley and fight, even though they leave no traces behind, that moment of the fight is caught on the video with activity/movement. Motion sensor movement, basically.
You are seriously confused. OP specifically said that you're fucked if there is no visual cue.
And you are seriously trying to kill the messenger.
And I'm saying there's ALWAYS a visual clue/cue, always. Either the bike is there one minute and gone another, or a fight breaks out and trashes the place from the fight. In the vast amount of cases, there's always a visual difference.
And in this case we're talking specifically about a bike, going missing.
Absolutely not true. Guy walks bye and shoots someone well offscreen. Momentary action with no visual cue before or after. Why are you arguing this useless point?
Ok but the text that you replied to, that you quoted, was "If the event lasts only a moment and leaves no visual cue (e.g. an assault), then binary search is practically useless." Emphasis mine. If you'd started out saying "there's ALWAYS a visual cue," then you likely wouldn't be getting dragged, but you started out arguing from this position without clarifying it, which makes it seem like you didn't know what you were talking about. You can't say that you can simply look for visual cues when the other person specified that there were none.
Your adding things that would allow a binary search work, but the question was in a situation where the only evidence is the conflict itself
2 guys enter one guy punches the other guy they both leave. Nothing is moved no blood was created,
you could not use a binary search effectively to duduce when it occurred.
What about this hypothetical scenario:
Suppose the objective is to review highway cam footage of the day to verify that a (non-speeding) car with a particular license plate drove past the area / used this route. The route is used 24/7 by many identical cars throughout the day and night, and that our target car is one such identical car, with the only difference being the license plate. We know on average cars that drive past this camera only appear for 3 seconds on the footage. How can binary search be used to find the car within 24 hours of footage, if the target car only appears for 3 seconds within the 24 hour video?
You either don't know what binary search is or you completely missed the context of this conversation
I'm a computer programmer. I know exactly what a binary search is. I've written binary searches before.
The search is to get you to the point where you can watch the video to see the crime happening, in hopes of indentifying the perpretrator.
Then you missed the point of this conversation
You're being intellectually dishonest, in an attempt to kill the message.
This is what was said in the origional OP pic...
Yes, but, as you noted in an earlier post, that isn't what you're responding to. The point of the post you stated you are responding to is: if an event occurs that leaves no change to the visual context before and after the occurrence, then binary search is ineffective.
The fact that you're wasting this much time trying to defend such a simple error is confusing. The reasonable response is, "oh, yes, in that particular case, binary search is ineffective."
Binary search only works on sorted data, i.e. you know which side of the mid point is pointing towards the incident. If the incident leaves no trail, you can't know whether you can discard the left side or the right side, making it a complicated linear search at that moment.
There's a moment where the bike is there, then another when its not. The whole video, either way, will either from the beginning up to the point of theft have the bike there, or NOT have the bike there from the point of theft to the end of the video. The marker is the removal of the bike from the video lens.
But the comment you replied to wasn't talking about bike thefts specifically, it was talking about unspecified situations that don't leave traces. You responded to someone saying that binary search doesn't work in situations that don't leave cues not by arguing against the premise (e.g. "but no such event exists, everything leaves cues"), but by telling them that you simply have to look for the cues from the hypothetical event that didn't leave any.
That doesn't apply to the comment you replied to.
Screw you, and your gatekeeping censoring.
I replied, saying the comment is not correct, and I gave reasons why, which are valid reasons.
Your reasons for why they were incorrect about a binary search being useless in situations that don't leave visual cues is that you can simply look for the visual cues lmao, that's not valid at all