Hello Codeforces!

Recently i observed that i am too bad with problems that require -:

1. Tricky observations or lots of observation

• Reduction Game
• Mismatched Socks

• Magic Grid
• Knights

• Two Groups
• Chef and Two Queens

Failed to Solve easy problems like Knights , Two Groups hurt a lot.

No matter, whether these problems rated less than my current rating in difficulty, i rarely solve them completely by own.

So here, i request you to suggest your effective strategy to tackle such problems.
Also, Suggest me more problems of these Kind to practice.

I am using g++/MINGW on Windows. I observe that it takes lot of time to build c++ programme. Programme written on language like java or python build almost 10 times faster in my system. May anyone suggest what changes i need to make in order to make c++ build as faster as others.