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Tag: Binary Search

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Binary Search

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Updated Apr 24, 2026
Binary Search Challenges
flag.txt
minaminao

minaminao

Misc
115 solves

flag.txt

Daily AlpacaHackTopic: GeneralReleased: Mar 15, 2026

115 solves
Misc

by

minaminao

minaminao

🦙 < flag is in flag.txt

Beginner Hint 1 (AI-translated)
  • From the problem statement, you can see that the flag is in flag.txt. However, if you try to download flag.txt, the download never finishes.
  • This is because the size of flag.txt is extremely large: 8192 PB. In fact, Chrome shows the remaining time as 2,147,483,647 days, so downloading the entire file is practically impossible.
  • If you extract source.tar.gz and check the distributed files, you will see that server.py creates a pseudo-large flag.txt.
Beginner Hint 2 (AI-translated)
  • Reading the comments in server.py, it says the contents of flag.txt are simply like Flag is ....................Alpaca{REDACTED}!!!!!!!!!!!!!!!!!!!!.
  • If you read the read function, you can confirm this behavior and see that the . and ! parts are extremely long.
  • So how can you obtain the flag portion?
Beginner Hint 3 (AI-translated)
  • There is a mechanism to download only a part of a file. Try using it.
  • This challenge is explained in Japanese on the YouTube channel "Full Weak Engineer"! https://youtu.be/WDETRIsCSHE
source.tar.gz

NOTE: This challenge have attachments that cannot be downloaded unless an instance is spawned.

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