QTREE  Query on a tree
You are given a tree (an acyclic undirected connected graph) with N nodes, and edges numbered 1, 2, 3...N1.
We will ask you to perfrom some instructions of the following form:
 CHANGE i ti : change the cost of the ith edge to ti
or  QUERY a b : ask for the maximum edge cost on the path from node a to node b
Input
The first line of input contains an integer t, the number of test cases (t <= 20). t test cases follow.
For each test case:
 In the first line there is an integer N (N <= 10000),
 In the next N1 lines, the ith line describes the ith edge: a line with three integers a b c denotes an edge between a, b of cost c (c <= 1000000),
 The next lines contain instructions "CHANGE i ti" or "QUERY a b",
 The end of each test case is signified by the string "DONE".
There is one blank line between successive tests.
Output
For each "QUERY" operation, write one integer representing its result.
Example
Input: 1 3 1 2 1 2 3 2 QUERY 1 2 CHANGE 1 3 QUERY 1 2 DONE Output: 1 3
hide comments
yyy_ugly:
20150415 08:50:44
yyy handsome ahead.............. 

lcr88888:
20150414 13:55:35
YYY is handsome. Last edit: 20150414 14:08:43 

lcr88888:
20150414 13:55:26
呔！ Last edit: 20150414 14:11:26 

chenyushuo:
20150401 03:08:18
I have got Accepted! Last edit: 20150401 03:09:30 

krish:
20150217 22:07:37
very good problem.


uttom:
20150127 06:21:18
I got WA


changjianbin:
20150125 02:51:45
233 

Prime:
20150101 16:15:15
This problem is so good!My program is accpeted!But I want to know how to solve it by link cut tree.Who can help me? 

hippie:
20141228 16:57:57
Don't use string and cin for the words in input > will cause TLE. Use char array and scanf instead. Wasted 4 hours on such a stupid issue. Last edit: 20141228 16:58:25 

‡■■Lãng du■■‡:
20141030 17:04:44
My solution, complexity O(logn ^2) for each "query" and O(logn) for each "Change"??? Is the time limit so low ?? Last edit: 20141030 22:54:43 
Added by:  ThanhVy Hua 
Date:  20050608 
Time limit:  1s 
Source limit:  15000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
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