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
amira3:
2024-08-10 11:54:43
Use query decomposition and decompose each query into sqrt(number of queries) and for each block of queries, process DFS and sparse table, and for every change in each query, after changing it to answer other queries you can just check if the edge is in the path from a to b or no (you can check this using LCA) and etc, overall time complexity : O(n * sqrt * log) Last edit: 2024-08-10 12:31:03 |
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luozhihe:
2024-01-09 16:05:54
TLE c++ please help me
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tobiasveiga:
2023-12-01 13:40:59
TIP: Assume nodes are numbered starting from 0 (unlike the edges...) |
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saiprasad_27:
2022-06-21 00:32:34
@t_l_enough same it is running fine on my computer but don't know why I'm getting SIGSEGV :(...
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vladislav11:
2022-06-08 18:44:41
https://cp-algorithms.com/graph/hld.html#implementation Last edit: 2022-06-08 18:45:01 |
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badmachine77:
2022-05-08 14:20:42
does anyone with AC want to get in touch and send me a solution because I am really struggling on this one ;( |
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kanisht09:
2022-01-11 20:40:23
thanks @princemishra |
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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 |
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whhsteven:
2021-10-31 08:24:39
Well, thank you. Last edit: 2021-10-31 08:25:03 |
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diwakar0:
2021-08-25 07:58:20
TLE in JAVA same code in CPP is ACCEPTED |
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 guile SCM qobi ST TEXT WHITESPACE |