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
- QUERY a b : ask for the maximum edge cost on the path from node a to node b
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.
For each "QUERY" operation, write one integer representing its result.
Input: 1 3 1 2 1 2 3 2 QUERY 1 2 CHANGE 1 3 QUERY 1 2 DONE Output: 1 3
My solution, complexity O(logn ^2) for each "query" and O(logn) for each "Change"??? Is the time limit so low ??Last edit: 2014-10-30 22:54:43
How many queries are there at most?
Finally Accepted! Values are non-neg always, no tricky test data but definitely difficult to debug.Last edit: 2013-12-01 20:28:19
lots of ambiguous things
Do all numbers have to be >=0? Can edges have negative weights?
|Added by:||Thanh-Vy Hua|
|Cluster:||Cube (Intel G860)|
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