A collection of algorithms

Competition Notes

• Runtime Error: Check memory limits, are there implicit conditions?
• Runtime Error: Do all declared functions return? If a function is int, make sure it returns something!
• Be generous with data type limits: 2,147,483,647 (int), 9,223,372,036,854,775,807 (ll)
• Usually, just set to ll.
• Offline query
• Probabilistic method (anything to do with 1/2)
• Mod can be negative! Do NOT use if (x%2 == 1). Rather, use if (x%2 != 0)

Facebook Hacker Cup

• ulimit -s unlimited
• In-program
• Compiler optimisation -O2

Debugging

• Index array last (caches)
• long long instead of int
• Array size, ordering, increments
• TLE: use '\n' instead of endl (no intermediate flush)

Resources

• Stanford's ICPC Notebook
• CP Algorithms