Crazy Bobo
Time Limit: 6000/3000 MS (Java/Others) Memory Limit: 131072/65536 K (Java/Others)
Total Submission(s): 218 Accepted Submission(s): 60
Problem Description
Bobo has a tree,whose vertices are conveniently labeled by 1,2,...,n.Each node has a weight
wi. All the weights are distrinct.
A set with m nodes
v1,v2,...,vm is a Bobo Set if:
- The subgraph of his tree induced by this set is connected.
- After we sort these nodes in set by their weights in ascending order,we get
u1,u2,...,um,(that is,
wui<wui+1 for i from 1 to m-1).For any node
x in the path from
ui to
ui+1(excluding
ui and
ui+1),should satisfy
wx<wui.
Your task is to find the maximum size of Bobo Set in a given tree.
Input
The input consists of several tests. For each tests:
The first line contains a integer n (
1≤n≤500000). Then following a line contains n integers
w1,w2,...,wn (
1≤wi≤109,all the
wi is distrinct).Each of the following n-1 lines contain 2 integers
ai and
bi,denoting an edge between vertices
ai and
bi (
1≤ai,bi≤n).
The sum of n is not bigger than 800000.
Output
For each test output one line contains a integer,denoting the maximum size of Bobo Set.
Sample Input
7 3 30 350 100 200 300 400 1 2 2 3 3 4 4 5 5 6 6 7
Sample Output
题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5325
解题思路:反正我是智商余额不足。。。
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AC代码:顺着题解思路DFS了一下= =
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