现在准备查询log日志文件，看下被操作的原因是什么

Problem Description Farmer John wants to set up a telephone line at his farm. Unfortunately, the phone company is uncooperative, so he needs to pay for some of the cables required to connect his farm

Here 典中之典！！ 解题思路 可选k条边代价为0如何决策？   将到当前位置选择了几条代价为0的边放入状态，即若当前状态选的边数小于，则可以进行决策，是否选择当前边，若选，则，否则若当前状态选的边数等于，则只能 考虑分层图，建k层（实际上就是将上一种方法中多一维记录来区别状态），改为用点的标号区分）对于每条边，向层连一条相同但代价为0的边同层连代价为的边最终输出第k层的

Time Limit: 3000MS Memory limit: 65536K 题目描述In St Petersburg phone numbers are formatted as “XXX–XX–XX”, where the first three digits represent index of the Automated Telephone Exchange (ATE). Each AT