Recently learned about the dynamic dp, the feeling did not imagine the difficulty.
Dynamic DP
The DP is so simple:
To the tree, each point to a weight, find what the maximum weight independent set.
This DP is dynamic:
To the tree, each point to a weight has changed everywhere, each time seeking to change what the maximum weight independent set.
Digression:
($ NOIP2018 $ defend the kingdom)
Gangster: $ dp $ dynamic board directly seconds.
Fairy: This is what Ah let me think ...... multiply? (Spot is then cut off)
In addition to big brother except gods besides Me: knock violence.
:( I misread the question of explosive eggs)
Several pre-knowledge:
(1) a heavy chain split
Select the most points subtree sons son when heavy tree section.
Several re-sectional properties:
1. The end must be leaves. (Tree sectional continuity)
2. a heavy chain is a contiguous segment split heavy chain sequence. (Tree sectional continuity)
3. root go through any point of the light chain does not exceed $ $ logN article. ( Weight sectional characteristics )
4.……
(2) matrix
Take the famous moment due to meet in conjunction with the law can be used to accelerate the recurrence / partition.
Bigwigs do not know ye want to come up with the following operations:
$$\begin{pmatrix}a00&a01\\a10&a11\end{pmatrix}+\begin{pmatrix}b00&b01\\b10&b11\end{pmatrix} $$
$$= \begin{pmatrix}max(a00+b00,a01+b10)&max(a00+b10,a01+b11)\\max(a10+b00,a11+b10)&max(a10+b01,a11+b11)$$
This thing actually is associative ......