Heavy Light Trick:

Resource :

1. https://www.youtube.com/watch?v=zbV0IRWBNvU&t=7775s

2. https://www.youtube.com/watch?v=eBGa5w1nsEw&t=149s

3. https://www.youtube.com/watch?v=94E2ztsDdyI&list=PLWtSipmftM8qmo4ysAvS-aI4nc9nLM-uv&index=2

Practice :

1. https://mirror.codeforces.com/contest/349/problem/E

2. https://mirror.codeforces.com/contest/1468/problem/M

Tree Rerooting Technique:

Resource:

1. https://m.facebook.com/groups/341771679363942/permalink/1382998865241213/

Practice :

1. https://mirror.codeforces.com/contest/1187/problem/E?fbclid=IwAR3UQ_ksPZm-Y2OJGwvrK3HYyWHMACw0iFdtd7PYoZS98Y-nvfH11LqtthE

2. https://vjudge.net/problem/EOlymp-1180

3. https://mirror.codeforces.com/problemset/problem/1156/D

Tree to Array (Euler Tour on Tree):

Resource :

1. https://www.youtube.com/watch?v=0v--9nEFfAM&t=3156s

Practice :

1. https://lightoj.com/problem/aladdin-and-the-return-journe