CF150E.Freezing with Style
普及/提高-
通过率:0%
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题目描述
This winter is so... well, you've got the idea :-) The Nvodsk road system can be represented as n junctions connected with n−1 bidirectional roads so that there is a path between any two junctions. The organizers of some event want to choose a place to accommodate the participants (junction v ), and the place to set up the contests (junction u ). Besides, at the one hand, they want the participants to walk about the city and see the neighbourhood (that's why the distance between v and u should be no less than l ). On the other hand, they don't want the participants to freeze (so the distance between v and u should be no more than r ). Besides, for every street we know its beauty — some integer from 0 to 109 . Your task is to choose the path that fits in the length limits and has the largest average beauty. We shall define the average beauty as a median of sequence of the beauties of all roads along the path.
We can put it more formally like that: let there be a path with the length k . Let ai be a non-decreasing sequence that contains exactly k elements. Each number occurs there exactly the number of times a road with such beauty occurs along on path. We will represent the path median as number a⌊k/2⌋ , assuming that indexation starting from zero is used. ⌊x⌋ — is number х , rounded down to the nearest integer.
For example, if a=0,5,12 , then the median equals to 5 , and if a=0,5,7,12 , then the median is number 7 .
It is guaranteed that there will be at least one path with the suitable quantity of roads.
输入格式
The first line contains three integers n , l , r ( 1≤l≤r,n≤105 ).
Next n−1 lines contain descriptions of roads of the Nvodsk, each line contains three integers ai , bi , ci ( 1<=ai,bi<=n , 0<=ci<=109 , ai=bi ) — junctions ai and bi are connected with a street whose beauty equals ci .
输出格式
Print two integers — numbers of the junctions, where to accommodate the participants and set up the contests, correspondingly. If there are multiple optimal variants, print any of them.
输入输出样例
输入#1
6 3 4 1 2 1 2 3 1 3 4 1 4 5 1 5 6 1
输出#1
4 1
输入#2
6 3 4 1 2 1 2 3 1 3 4 1 4 5 2 5 6 2
输出#2
6 3
输入#3
5 1 4 1 2 1 1 3 4 3 4 7 3 5 2
输出#3
4 3
输入#4
8 3 6 1 2 9 2 3 7 3 4 7 4 5 8 5 8 2 3 6 3 2 7 4
输出#4
5 1
说明/提示
In the first sample all roads have the same beauty. That means that all paths of the positive length have the same median. Thus, any path with length from 3 to 4 , inclusive will be valid for us.
In the second sample the city looks like that: 1 - 2 - 3 - 4 - 5 - 6. Two last roads are more valuable and we should choose any path that contains both of them and has the suitable length. It is either the path between 2 and 6 or the path between 3 and 6 .