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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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2017-07-22 23:23:39
when dealing with levels of parents of nodes don't forget to check if parent[node][j] != -1 to avoid Run time error level[-1] |
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2017-07-21 10:21:40
Got segmentation fault in C++(g++4.3.2) but same solution got accepted in C++(gcc 6.3). |
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2017-07-21 02:45:39
Is it sufficient to answer each query in the order of the path from a to b ? |
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2017-07-13 09:10:16
there is one blank line between successive test cases -_- |
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2017-06-23 20:53:06
For the KTH query, will O(k) complexity pass? Or something else is required? Edit: O(logN + k) is sufficient. Last edit: 2017-06-23 21:43:03 |
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2017-05-25 17:26:38
AC after 4 WA. Feel good. I used RMQ on Level eulerian walk to get LCA and binary search on levels to get kth Ancestor |
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2017-03-02 00:06:42
This is way easier than QTREE; you don't need HLD, only LCA. You also DO NOT need long long; which you could infer from the input restrictions btw. |
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2016-10-29 21:07:15 Ashwani Gautam
can use hld, use long long int for anything related to summation of edges |
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2016-08-28 21:03:27
easy . sparse Matrix approach for LCA calculation. |
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2016-07-26 19:51:48
easy ;) confidence booster |