Module DP on tree

DP on tree

**Frequency: 6/10** DP, but on tree.

Resources

- [USACO: DP on trees](https://usaco.guide/gold/dp-trees?lang=cpp)

Problems

Tree coloring 381 / 401 1200
Tree coloring 2 322 / 325 1200
Maximum sum path 271 / 309 1300
Path with length k 263 / 271 1300
Subgraph 214 / 224 1300
Beautiful tree 188 / 194 1500
Company 148 / 155 1700
Zero tree 119 / 133 1700
Selfie 59 / 75 1800