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
t_l_enough: 2021-11-27 09:03:06

Why does my code(c++) runtime error (SIGSEGV)?

Last edit: 2021-11-27 09:05:23
whhsteven: 2021-10-31 08:24:39

Well, thank you.

Last edit: 2021-10-31 08:25:03
diwakar0: 2021-08-25 07:58:20

TLE in JAVA same code in CPP is ACCEPTED

adam____: 2021-08-23 17:59:05

AC, but HLD is just pain

princemishra: 2021-02-16 17:31:17

Last edit: 2021-03-11 15:22:43
princemishra: 2021-02-16 17:20:28

best place to study heavy light decompostion
https://discuss.codechef.com/t/tutorial-heavy-light-decomposition/69423
https://www.youtube.com/watch?v=LK-0QNShaPM

whhsteven: 2020-08-30 16:16:41

Not kidding. What's HLD? Please tell me...

Last edit: 2020-08-30 16:17:01
mhasan01: 2020-07-09 23:14:38

Nice problem to learn HLD :)

pareksha: 2020-05-01 10:04:49

If you are getting RE SIGSEGV, use void return type with functions not returning anything.

an09mous: 2020-03-22 19:46:14

There's no need to find LCA separately if you are using HLD.


Added by:Thanh-Vy Hua
Date:2005-06-08
Time limit:1s
Source limit:15000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:ADA95 ASM32 BASH BF C CSHARP CPP CLPS LISP sbcl LISP clisp D FORTRAN HASK ICON ICK JAVA LUA NEM NICE OCAML PAS-GPC PAS-FPC PERL PHP PIKE PRLG-swi PYTHON RUBY SCM qobi SCM guile ST TEXT WHITESPACE