QTREE - Query on a tree


You are given a tree (an acyclic undirected connected graph) with N nodes, and edges numbered 1, 2, 3...N-1.

We will ask you to perfrom some instructions of the following form:

  • CHANGE i ti : change the cost of the i-th 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 N-1 lines, the i-th line describes the i-th 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
devu: 2013-12-01 20:27:49

Finally Accepted! Values are non-neg always, no tricky test data but definitely difficult to debug.

Last edit: 2013-12-01 20:28:19
Mojtaba FayazBakhsh: 2013-08-22 18:59:00

lots of ambiguous things
Are the edge's cost positive?
could the new val of edges be more than 1000000?
Shall we print an empty blank between
different test?
could for QUERY a b: a = b?
...

Abhay Goel: 2013-01-03 16:06:58

Do all numbers have to be >=0? Can edges have negative weights?


Added by:Thanh-Vy Hua
Date:2005-06-08
Time limit:0.851s
Source limit:15000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
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