给一个联通图,有的是单向边,有的是双向边,问是否存在欧拉回路. 乍一看毫无思路,可以这样来搞,对于每条无向边,我们随便指定一个方向,看看是否能够做到所有点的度数之和为偶数. 接下来,对于我们指定的边,假设指定的是U->V,那么我们也同时在网络中设置一条同样的边,使得流量为1,最后如果某点的出入度只差不为0,那么我们把那个差除以2,这表示我们在这个点处至少需要改变多少条无向边的方向.对于出大于入的点,我们连源点,对于入大于出的点,我们连汇点,最后跑最大流看看所有的与源点和汇点的边能否满流即可. 一…

Sightseeing tour Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 9276   Accepted: 3924 Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beauti…

Euler Tour Tree最大的优点就是可以方便的维护子树信息,这点LCT是做不到的.为什么要维护子树信息呢..?我们可以用来做fully dynamic connectivity(online). Euler Tour Tree 维护将树中的边u--v变成u->v,v->u后的Euler Tour. 换根: 因为Euler Tour是一个环,那么我们可以在任意一个k->u的地方切断,然后把这段东西接到最后去,这样就把u变成根了 Link: 先换根,然后添加u->v与v->…

Tour Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 4307   Accepted: 1894 Description John Doe, a skilled pilot, enjoys traveling. While on vacation, he rents a small plane and starts visiting beautiful places. To save money, John must…

题目描述: 1015. Jill's Tour Paths Constraints Time Limit: 1 secs, Memory Limit: 32 MB Description Every year, Jill takes a bicycle tour between two villages. There are different routes she can take between these villages, but she does have an upper limit…

Sightseeing tour Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 8859   Accepted: 3728 Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beauti…

A quick tour of JSON libraries in Scala Update (18.11.2015): added spray-json-shapeless libraryUpdate (06.11.15): added circe library Some time ago I wrote a post on relational database access in Scala since I was looking for a library and there were…

Sightseeing tour Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 6986   Accepted: 2901 Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beauti…

Sightseeing tour   Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beautiful city. They want to construct the tour so that every street in the city is vis…

  Farm Tour Time Limit: 2MS   Memory Limit: 65536KB   64bit IO Format: %I64d & %I64u Description When FJ's friends visit him on the farm, he likes to show them around. His farm comprises N (1 <= N <= 1000) fields numbered 1..N, the first of whic…