single 7: http://acm.hust.edu.cn/vjudge/contest/view.action?cid=52662#overview
A 水题 http://www.cnblogs.com/someblue/p/4018976.html
B dfs序+线段树 http://www.cnblogs.com/someblue/p/4018968.html
C 并查集 http://www.cnblogs.com/someblue/p/4019001.html
D trie+bfs http://www.cnblogs.com/someblue/p/4018996.html
E
F 二分图匹配 http://www.cnblogs.com/someblue/p/4027628.html
single 8: http://acm.hust.edu.cn/vjudge/contest/view.action?cid=52807#overview psw: single8
single 9: http://acm.hust.edu.cn/vjudge/contest/view.action?cid=52921#overview psw: single9
single 10: http://acm.hust.edu.cn/vjudge/contest/view.action?cid=52892#overview psw: single0
single 11: http://acm.hust.edu.cn/vjudge/contest/view.action?cid=52890#overview psw: single1
single 12: http://acm.hust.edu.cn/vjudge/contest/view.action?cid=53194#overview psw: single2