As a matter of fact, I'm going to ask 9fans to volunteer cpu seconds to compute 25 queen problem using this. :)
You can estimate for computing power to do this. The task to get solution of N-queens problem can be divided into small independent pieces of tasks. We can get Open-MP style program qn24b-version1/omp from http://www.yuba.is.uec.ac.jp/~kis/nq/index.htm I transformed this program so that we can execute such like queen n i:j this means n-queens problem of task(piece) range i to j (You can get this program in co.aichi-u.ac.jp using cpu command and look /usr/arisawa/src/taskfs/Q/src/) I measured the time time queen n 0:1 0:1 means the first one piece. The result measured on 2.4GHz Xeon n time # of pieces 21 5s 41176 22 33s 49480 23 238s 64072 24 1751s 75516 25 13590s 95472 note that the time required to compute one piece increases rapidly -bash$ python Python 2.3 (#1, Sep 13 2003, 00:49:11) [GCC 3.3 20030304 (Apple Computer, Inc. build 1495)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> 13590*95472 1297464480 >>> 1297464480/(60*60*24*365) 41 >>> 41 years on single computer! 500 volunteers who can offer one month? I want rather 2000 9grid computers... Kenji Arisawa
