(更)第 N 题有一个 1/2 误写成 2
所以答案要再除以4
http://i.imgur.com/EkPTMlF.jpg
http://i.imgur.com/hHM48g7.jpg
http://i.imgur.com/EnfLXpn.jpg
http://i.imgur.com/lunBYyG.jpg
http://i.imgur.com/HanNGaX.jpg
http://i.imgur.com/fU2g0VF.jpg
http://i.imgur.com/LQorQSy.jpg
http://i.imgur.com/RXpvner.jpg
http://i.imgur.com/HGNOFns.jpg
http://i.imgur.com/fyAUuM3.jpg
(已授权公布)