算法分析与设计中的经典问题，利用回溯法解决背包问题，有详细的代码段。-Algorithm analysis and design of the classic problems, the use of backtracking to solve knapsack problem, there is a detailed code snippet.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.000978s ]
SELECT `a`.`aid`,`a`.`title`,`a`.`create_time`,`m`.`username` FROM `jrk_downrecords` `a` INNER JOIN `jrk_member` `m` ON `a`.`uid`=`m`.`id` WHERE `a`.`status` = 1 GROUP BY `a`.`aid` ORDER BY `a`.`create_time` DESC LIMIT 10 [ RunTime:0.063346s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001000s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001206s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.000985s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003202s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000841s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003718s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.018393s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001402s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 228139 [ RunTime:0.012519s ]
