这个程序是按照离散数学教材上给出的算法写的，是字典序的全排列算法。空间复杂度是O(n)，时间复杂度基本上是O(n^2)。缺点是只用于打印并没有储存所有的结果。-the procedure is in accordance with the materials on discrete mathematics algorithm is written, is a wholly-lexicographic order algorithm. Space complexity is O (n), is basically time complexity is O (n ^ 2). Only drawback is not for print, and store all the results.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001413s ]
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:0.074991s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001077s ]
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SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001073s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.002964s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000960s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003557s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.014016s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001167s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 122593 [ RunTime:0.058350s ]
