Codeforces Round 107 (Div. 1)
E
Freezing with Style
Codeforces
3000
原题
← D→
翻译中…

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 $10^{9}$. 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.

翻译中…

We can put it more formally like that: let there be a path with the length $*k*$. Let $*a*_{*i*}$ 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.

翻译中…

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 $7$.

翻译中…

It is guaranteed that there will be at least one path with the suitable quantity of roads.

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Input

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The first line contains three integers $*n*$, $*l*$, $*r*$ ($1 ≤ *l* ≤ *r* < *n* ≤ 10^{5}$).

翻译中…

Next $*n* - 1$ lines contain descriptions of roads of the Nvodsk, each line contains three integers $*a*_{*i*}$, $*b*_{*i*}$, $*c*_{*i*}$ ($1 ≤ *a*_{*i*}, *b*_{*i*} ≤ *n*$, $0 ≤ *c*_{*i*} ≤ 10^{9}$, $*a*_{*i*} ≠ *b*_{*i*}$) — junctions $*a*_{*i*}$ and $*b*_{*i*}$ are connected with a street whose beauty equals $*c*_{*i*}$.

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Output

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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.

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Note

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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.

翻译中…

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 $6$.

翻译中…

样例

Input #1
6 3 4
1 2 1
2 3 1
3 4 1
4 5 1
5 6 1
Output #1
4 1
InputCopy OutputCopy
Input #2
6 3 4
1 2 1
2 3 1
3 4 1
4 5 2
5 6 2
Output #2
6 3
InputCopy OutputCopy
Input #3
5 1 4
1 2 1
1 3 4
3 4 7
3 5 2
Output #3
4 3
InputCopy OutputCopy
Input #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
Output #4
5 1
InputCopy OutputCopy
题目信息
题号
150E
时间限制
7 s
内存限制
256 MB
标签
二分
数据结构
分治
树

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。