Attached is an email from our classmate, which shows the numbers of
solutions for a general X-queen problem.

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Hi.... Dear prof. Jang:

Here's something you might be interested in.

There are 4 kind(s) of solutions in 4 queens question .
There are 10 kind(s) of solutions in 5 queens question .
There are 4 kind(s) of solutions in 6 queens question .
There are 40 kind(s) of solutions in 7 queens question .
There are 92 kind(s) of solutions in 8 queens question .
There are 352 kind(s) of solutions in 9 queens question .
There are 724 kind(s) of solutions in 10 queens question .
There are 2680 kind(s) of solutions in 11 queens question .
There are 14200 kind(s) of solutions in 12 queens question .
There are 365596 kind(s) of solutions in 14 queens question .
There are 2279184 kind(s) of solutions in 15 queens question .
There are 14772512 kind(s) of solutions in 16 queens question .  

Do NOT consider rotate , mirror, etc. 

As you see, the solutions grows faster than exponential fun.
I was wondering if there exist better algorithms in sloving
X-queens problems.

BTW, you mentioned that there is "makemaze" function in Matlab. 
Do you know what's the algorithm in Matlab?

Expect for your answers.

Regards, 
your student 820914
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