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 222 / 234 1200
Tree coloring 2 188 / 190 1200
Maximum sum path 157 / 181 1300
Path with length k 148 / 156 1300
Subgraph 119 / 127 1300
Beautiful tree 108 / 110 1500
Company 75 / 82 1700
Zero tree 64 / 73 1700
Selfie 7 / 8 1800