Tree
| Time Limit: 5000MS |
|
Memory Limit: 131072K |
| Total Submissions: 3189 |
|
Accepted: 897 |
Description
You are given a tree with N nodes. The tree’s nodes are numbered 1 throughN and its edges are numbered 1 through N − 1. Each edge is associated with a weight. Then you are to execute a series of instructions on the tree. The instructions can be one of the following forms:
CHANGE i v |
Change the weight of the ith edge to v |
NEGATE a b |
Negate the weight of every edge on the path from a to b |
QUERY a b |
Find the maximum weight of edges on the path from a to b |
Input
The input contains multiple test cases. The first line of input contains an integert (t ≤ 20), the number of test cases. Then follow the test cases.
Each test case is preceded by an empty line. The first nonempty line of its containsN (N ≤ 10,000). The next N − 1 lines each contains three integersa, b and c, describing an edge connecting nodes a and b with weight c. The edges are numbered in the order they appear in the input. Below them are the instructions, each sticking to the specification above. A lines with the word “DONE” ends the test case.
Output
For each “QUERY” instruction, output the result on a separate line.
Sample Input
1
3
1 2 1
2 3 2
QUERY 1 2
CHANGE 1 3
QUERY 1 2
DONE
Sample Output
1
3
题意：给定一颗树，有三种操作:（1）改变第i条边的权值，（2）将从u到v路径上的权值取反，（3）查询从u到v路径上的最大权。
解题思路：首先轻重链剖分，然后线段树维护最大值，最小值，以及取反标记。
代码：
/* ***********************************************
Author :xianxingwuguan
Created Time :2014-1-24 13:55:10
File Name :2.cpp
************************************************ */
#pragma comment(linker, "/STACK:102400000,102400000")
#include
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