The Line on Recursion
Recall the two parts of a recursive solution:
- If the problem is easy, solve it immediately.
 
- If the problem can't be solved immediately,
    divide it into smaller problems, then:
    
    - Solve the smaller problems by applying this procedure to each of them.
 
    
     
In terms of the "divide a line into 16 pieces" problem these are:
- If a line is small enough, don't divide it.
 
- Divide the line into two pieces.
    
    - Apply this process to each of the two pieces.