QTREE5  Query on a tree V
You are given a tree (an acyclic undirected connected graph) with N nodes. The tree nodes are numbered from 1 to N. We define dist(a, b) as the number of edges on the path from node a to node b.
Each node has a color, white or black. All the nodes are black initially.
We will ask you to perfrom some instructions of the following form:
 0 i : change the color of ith node(from black to white, or from white to black).
 1 v : ask for the minimum dist(u, v), node u must be white(u can be equal to v). Obviously, as long as node v is white, the result will always be 0.
Input
 In the first line there is an integer N (N <= 100000)
 In the next N1 lines, the ith line describes the ith edge: a line with two integers a b denotes an edge between a and b.
 In the next line, there is an integer Q denotes the number of instructions (Q <= 100000)
 In the next Q lines, each line contains an instruction "0 i" or "1 v"
Output
For each "1 v" operation, print one integer representing its result. If there is no white node in the tree, you should write "1".
Example
Input: 10 1 2 1 3 2 4 1 5 1 6 4 7 7 8 5 9 1 10 10 0 6 0 6 0 6 1 3 0 1 0 1 1 3 1 10 1 4 1 6 Output: 2 2 2 3 0
hide comments
Rizvee:
20180510 16:37:48
do O(LogN * LogN) per query get AC ? I am consistently getting TLE. I tried to implement centroid decomposition here. 

siva2697:
20180331 15:19:26
BEST QUESTION ON TREES MUST DO. try implementing priority_queue its fun when u get it AC. DID with centroid Decomposition. I wonder how HLD approach would be for this..? 

tanavya:
20180305 05:36:29
If anyone wants to learn the algorithm used to solve this problem, read this amazing blog: https://threadsiiith.quora.com/CentroidDecompositionofaTree :)


alejf:
20170303 17:40:07
I'm trying to use a Centroid Decomposition to solve this problem, but still having WA. All the cases i've tested by my own give the right solution, so anyone knows of some border cases??? Thanks.


sinh_ngu_10i:
20170204 06:16:20
Anyone know how to use HLD for this problem ? 

Ronak Vaghela:
20161221 23:07:20
Nice Question :)


Vadym:
20151017 09:30:09
7 line of statement: "alway" > it should be "always" 
Added by:  Qu Jun 
Date:  20080813 
Time limit:  0.714s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  XunYunbo, modified from ZJOI07 