Impression of tracing recursion (week 4)

  This week and last week we learnt recursion and tracing recursion. 
   It is amazing, for example, the method calls itself in its body, which makes a loop. It is more convenient than to use recursion than for loop or while loop, however, the thinking process is much more complicated than for loop and while loop. 
   I found myself have trouble writing complex recursion function, but I realized tracing recursion is quite useful. I guess that's the reason why we learnt how to trace them at first. 
   Here are the details and steps about my solution. When I encounter some problem when writing recursive function, I try to "tracing" it firstly. For instance, try to figure out what I want at each step. For most of the time, I need to guess with my instinct, then trace it. When error occurs, I stop tracing and then fix my guess then restart. After several loops, I can find the right answer. However, it's kind of time-wasting, but is still quite useful.