未完成

http://yjbys.com/bishi/timu/638994.html

http://wenku.baidu.com/view/5bea853f59eef8c75fbfb3a8.html

http://zhidao.baidu.com/question/439570400.html?loc_ans=1070374894

http://www.jb51.net/tools/zhengze.html

http://wenku.baidu.com/link?url=y-FSWMM8QXKPVwcdUFD043NWtmGy8SEegim8r-3w7ZYzP4KLmuXnBf3eIKX5DH2i6QuRGlPY3L6eSoJCYA-7hCKPHc_TIveZcFtzekeFPP7

http://yjbys.com/bishi/timu/639014.html

http://hihocoder.com/problemset/problem/1000