http://acm.hdu.edu.cn/showproblem.php?pid=1671
http://acm.hdu.edu.cn/showproblem.php?pid=1251
http://acm.hdu.edu.cn/showproblem.php?pid=1075
http://acm.hdu.edu.cn/showproblem.php?pid=1671
http://acm.hdu.edu.cn/showproblem.php?pid=1251
http://acm.hdu.edu.cn/showproblem.php?pid=1075
转载于:https://www.cnblogs.com/Kiven5197/p/6545049.html