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## HDU 6023 ping ping ping

Time Limit: 2000/1000 MS (Java/Others) LCA + 贪心 The structure of the computer room in Northeastern University is pretty miraculous. There are $n$ servers, some servers connect to the gateway whose $IP$ address is $0$ directly. All servers are connected with each other by $n$ netting twines. It is said that this structure is favorable for maintaining physical problem of servers. （更多…）