P19220 [HackerRank] Heavy light 2 white falcon
提高-
题目描述

White Falcon was amazed by what she can do with heavy-light decomposition on trees. As a resut, she wants to improve her expertise on heavy-light decomposition. Her teacher gave her an another assignment which requires path updates. As always, White Falcon needs your help with the assignment.

You are given a tree with $N$ nodes and each node's value $val_i$ is initially $0$.

Let's denote the path from node $\mbox{u}$ to node $\boldsymbol{\nu}$ like this: $p_1,p_2,p_3,\ldots,p_k$, where $p_1=u$ and $p_k=v$, and $p_i$ and $\textbf{p}_{i+1}$ are connected.

The problem asks you to operate the following two types of queries on the tree:

"1 u v x" Add $\boldsymbol{x}$ to $val_{p_1}$, $2x$ to $val_{p_2}$, $3x$ to $val_{p_3}$, ..., $kx$ to $val_{p_k}$.
"2 u v" print the sum of the nodes' values on the path between $\mbox{u}$ and $\boldsymbol{\nu}$ at modulo $10^9+7$.

Input Format

First line cosists of two integers $N$ and $Q$ seperated by a space.

Following $N-1$ lines contains two integers which denote the undirectional edges of the tree.

Following $Q$ lines contains one of the query types described above.

Note: Nodes are numbered by using 0-based indexing.

Constraints

$1\le N,Q\le50000$

$0\leq x<10^9+7$

Output Format

For every query of second type print a single integer.

Sample Input
3 2
0 1
1 2
1 0 2 1
2 1 2

Sample Output
5

Explanation

After the first type of query, $val_0=1,val_1=2,val_2=3$. Hence the answer of the second query is $2+3=5$.

输入格式

见题面

输出格式

见题面

样例输入
3 2 0 1 1 2 1 0 2 1 2 1 2
样例输出
5