A Colourful Prospect

Source: Codeforces 933C

1. Read the problem and summarise the task requirements.
   • Try to keep your response to a couple of sentences.
2. Do some examples with pen and paper.
   • There are not too many cases to consider.
3. In lectures, we developed a method to check whether line segments intersect.
   • How could you tell whether a circle intersects with a line?
   • Therefore, how could you tell whether two circles intersect?

4. Design an algorithm to solve the problem.

5. Analyse the time complexity of your algorithm and estimate its running time.

6. Implement this algorithm in code.
   • Reflector:
     • What potential pitfalls can you think of?
     • Write some tests to check for these pitfalls.
   • Other group members:
     • Write a program which solves the problem.
   • Run your tests and debug if necessary.
7. Submit your program for judging!
   • Debug as required.