I am studying Unity AI by studying books, Untiy AI game programming  2/e.

However, I have a problem.

but, I don't know where the problem is..... 

Please help me.. T^T

A Star Pathfinding.zip

It will help if you describe what the problem is. Please don't expect users to download your entire code, build it, execute it, try to diagnose what the problem is (without even know what the program should be doing), and then debug the entire thing for you.

What behavior are you expecting? What behavior are you seeing instead and why is this a problem? What have you tried to do to fix it yourself?

1 minute ago, jpetrie said:

It will help if you describe what the problem is. Please don't expect users to download your entire code, build it, execute it, try to diagnose what the problem is (without even know what the program should be doing), and then debug the entire thing for you.

What behavior are you expecting? What behavior are you seeing instead and why is this a problem? What have you tried to do to fix it yourself?

Unity stops because of a crash when the start button is pressed... 

Please take a look at this. Particular, at point 4.

What kind of crash? What is the exact error message? What's the callstack at the point where you break into the debugger? Have you put breakpoints in the function that is called when you click "start" and stepped through the code, looking for things that seem wrong?

24 minutes ago, Titane said:

Unity stops because of a crash when the start button is pressed... 

 

If The Unity editor is crashing before you can read the console output, it also writes output to a logfile that you can check even if it completely crashes:

https://docs.unity3d.com/Manual/LogFiles.html

Usually Unity itself will only crash because of stack overflows due to unbounded recursion, or due to really arcane stuff that I doubt you're getting into yet.  Since you mention A* my guess is that your code contains unbounded recursion.