CF1060F.Shrinking Tree

普及/提高-

通过率:0%

AC君温馨提醒

该题目为【codeforces】题库的题目,您提交的代码将被提交至codeforces进行远程评测,并由ACGO抓取测评结果后进行展示。由于远程测评的测评机由其他平台提供,我们无法保证该服务的稳定性,若提交后无反应,请等待一段时间后再进行重试。

题目描述

Consider a tree TT (that is, a connected graph without cycles) with nn vertices labelled 11 through nn . We start the following process with TT : while TT has more than one vertex, do the following:

  • choose a random edge of TT equiprobably;
  • shrink the chosen edge: if the edge was connecting vertices vv and uu , erase both vv and uu and create a new vertex adjacent to all vertices previously adjacent to either vv or uu . The new vertex is labelled either vv or uu equiprobably.

At the end of the process, TT consists of a single vertex labelled with one of the numbers 1,,n1, \ldots, n . For each of the numbers, what is the probability of this number becoming the label of the final vertex?

输入格式

The first line contains a single integer nn ( 1n501 \leq n \leq 50 ).

The following n1n - 1 lines describe the tree edges. Each of these lines contains two integers ui,viu_i, v_i — labels of vertices connected by the respective edge ( 1ui,vin1 \leq u_i, v_i \leq n , uiviu_i \neq v_i ). It is guaranteed that the given graph is a tree.

输出格式

Print nn floating numbers — the desired probabilities for labels 1,,n1, \ldots, n respectively. All numbers should be correct up to 10610^{-6} relative or absolute precision.

输入输出样例

  • 输入#1

    4
    1 2
    1 3
    1 4
    

    输出#1

    0.1250000000
    0.2916666667
    0.2916666667
    0.2916666667
    
  • 输入#2

    7
    1 2
    1 3
    2 4
    2 5
    3 6
    3 7
    

    输出#2

    0.0850694444
    0.0664062500
    0.0664062500
    0.1955295139
    0.1955295139
    0.1955295139
    0.1955295139
    

说明/提示

In the first sample, the resulting vertex has label 1 if and only if for all three edges the label 1 survives, hence the probability is 1/23=1/81/2^3 = 1/8 . All other labels have equal probability due to symmetry, hence each of them has probability (11/8)/3=7/24(1 - 1/8) / 3 = 7/24 .

首页