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QTREE2 - Query on a tree II |
You are given a tree (an undirected acyclic connected graph) with N nodes, and edges numbered 1, 2, 3 ...N-1. Each edge has an integer value assigned to it, representing its length.
We will ask you to perform some instructions of the following form:
- DIST a b : ask for the distance between node a and node b
or - KTH a b k : ask for the k-th node on the path from node a to node b
Example:
N = 6
1 2 1 // edge connects node 1 and node 2 has cost 1
2 4 1
2 5 2
1 3 1
3 6 2
Path from node 4 to node 6 is 4 → 2 → 1 → 3 → 6
DIST 4 6 : answer is 5 (1 + 1 + 1 + 2 = 5)
KTH 4 6 4 : answer is 3 (the 4-th node on the path from node 4 to node 6 is 3)
Input
The first line of input contains an integer t, the number of test cases (t <= 25). 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 <= 100000)
- The next lines contain instructions "DIST a b" or "KTH a b k"
- The end of each test case is signified by the string "DONE".
There is one blank line between successive tests.
Output
For each "DIST" or "KTH" operation, write one integer representing its result.
Print one blank line after each test.
Example
Input: 1 6 1 2 1 2 4 1 2 5 2 1 3 1 3 6 2 DIST 4 6 KTH 4 6 4 DONE Output: 5 3
Added by: | Thanh-Vy Hua |
Date: | 2006-08-27 |
Time limit: | 1s |
Source limit: | 15000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ERL JS-RHINO NODEJS PERL6 VB.NET |
Resource: | Special thanks to Ivan Krasilnikov for his alternative solution |
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2021-09-15 19:04:07
If you use LCA for this problem, remember to check if 'a' and 'b' in a same branch and 'a' is closer to the root than 'b' This case cost me some WA .-. |
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2020-07-10 00:46:46
Nice, used HLD, although binary lifting would probably be better |
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2020-06-21 06:43:11
A must do question to learn LCA. Last edit: 2020-06-21 06:43:28 |
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2020-05-13 19:13:04
Updated: AC I am using binary lifting approach but getting the wrong answer. Last edit: 2020-05-14 09:42:54 |
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2020-05-09 15:14:03
just check your preprocessing fn if you are getting segmentation fault |
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2020-04-25 10:36:47
Easy but good problem :) |
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2020-03-11 17:31:40
Did it using binary lifting. A must do problem if you're learning LCA. |
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2020-02-22 15:48:43
Updated:AC I don't know why i am getting wrong answer probably not even passed the sample test case. But running in local machine my code gives right output. Can anybody help me please? Last edit: 2020-02-22 16:58:08 |
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2019-08-03 09:02:01
Don't forget to print one blank line after each test case. |
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2019-05-22 22:16:44
Easy to solve with sqrt decompostion, as there are no updates. |