DZY Loves Connecting Accepts: 16 Submissions: 169 Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 262144/262144 K (Java/Others) 问题描述 DZY有一棵nn个结点的无根树，结点按照1\sim n1∼n标号。DZY喜欢树上的连通