Practical tips debugging deep recursion?

Question

I\'m working on a board game algorithm where a large tree is traversed using recursion, however, it\'s not behaving as expected. How do I handle this and what are you experience

Answer 1

Since you say that the traversal is not working as expected, I assume you have some idea of where things may go wrong. Then inspect the code to verify that you have not overlooked something basic.

After that I suggest you set up some simple unit tests. If they pass, then keep adding tests until they fail. If they fail, then reduce the tests until they either pass or are as simple as they can be. That should help you pinpoint the problems.

If you want to debug as well, I suggest you employ conditional breakpoints. Visual Studio lets you modify breakpoints, so you can set conditions on when the breakpoint should be triggered. That can reduce the number of iterations you need to look at.

Answer 2

I once had a similar problem when I was developing an AI algorithm to play a Tetris game. After trying many things a loosing a LOT of hours in reading my own logs and debugging and stepping in and out of functions what worked out for me was to code a fast visualizer and test my code with FIXED input.

So, if time is not a problem and you really want to understand what is going on, get a fixed board state and SEE what your program is doing with the data using a mix of debug logs/output and some sort of your own tools that shows information on each step.

Once you find a board state that gives you this problem, try to pin-point the function(s) where it starts and then you will be in a position to fix it.