抱歉这是鸽子贴。

树形dp

[x][[POI2014]HOT-Hotels](https://www.luogu.org/problemnew/show/P3565)
[x][[HAOI2015]树上染色](https://www.luogu.org/problemnew/show/P3177)
[x][[HNOI/AHOI2018]道路](https://www.luogu.org/problemnew/show/P4438)
[x][HAOI2018苹果树](https://www.luogu.org/problemnew/show/P4492)
[x][[USACO10MAR]伟大的奶牛聚集](https://www.luogu.org/problemnew/show/P2896)
[x][[ZJOI2008]骑士](https://www.luogu.org/problemnew/show/P2607)