Puzzles
Puzzles
Barney lives in country USC (United States of Charzeh). USC has n cities numbered from 1 through n and n - 1 roads between them. Cities and roads of USC form a rooted tree (Barney's not sure why it is rooted). Root of the tree is the city number 1. Thus if one will start his journey from city 1, he can visit any city he wants by following roads.

Some girl has stolen Barney's heart, and Barney wants to find her. He starts looking for in the root of the tree and (since he is Barney Stinson not a random guy), he uses a random DFS to search in the cities. A pseudo code of this algorithm is as follows:
let starting_time be an array of length n
current_time = 0
dfs(v):
current_time = current_time + 1
starting_time[v] = current_time
shuffle children[v] randomly (each permutation with equal possibility)
// children[v] is vector of children cities of city v
for u in children[v]:
dfs(u)
As told before, Barney will start his journey in the root of the tree (equivalent to call dfs(1)).
Now Barney needs to pack a backpack and so he wants to know more about his upcoming journey: for every city i, Barney wants to know the expected value of starting_time[i]. He's a friend of Jon Snow and knows nothing, that's why he asked for your help.
The first line of input contains a single integer n (1 ≤ n ≤ 105) — the number of cities in USC.
The second line contains n - 1 integers p2, p3, ..., pn (1 ≤ pi < i), where pi is the number of the parent city of city number i in the tree, meaning there is a road between cities numbered pi and i in USC.
In the first and only line of output print n numbers, where i-th number is the expected value of starting_time[i].
Your answer for each city will be considered correct if its absolute or relative error does not exceed 10 - 6.
7
1 2 1 1 4 4
1.0 4.0 5.0 3.5 4.5 5.0 5.0
12
1 1 2 2 4 4 3 3 1 10 8
1.0 5.0 5.5 6.5 7.5 8.0 8.0 7.0 7.5 6.5 7.5 8.0
分析:不是太懂,貌似不在当前节点的子树中,却在他父亲的子树中的节点,先比他拜访的概率是0.5;
官方题解:http://codeforces.com/blog/entry/46031
代码:
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <climits>
#include <cstring>
#include <string>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <vector>
#include <list>
#include <ext/rope>
#define rep(i,m,n) for(i=m;i<=n;i++)
#define rsp(it,s) for(set<int>::iterator it=s.begin();it!=s.end();it++)
#define vi vector<int>
#define pii pair<int,int>
#define mod 1000000007
#define inf 0x3f3f3f3f
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define ll long long
#define pi acos(-1.0)
const int maxn=1e5+;
const int dis[][]={{,},{-,},{,-},{,}};
using namespace std;
using namespace __gnu_cxx;
ll gcd(ll p,ll q){return q==?p:gcd(q,p%q);}
ll qpow(ll p,ll q){ll f=;while(q){if(q&)f=f*p;p=p*p;q>>=;}return f;}
int n,m,child[maxn],fa[maxn];
double vis[maxn];
vi p[maxn];
int dfs(int now)
{
int cnt=;
for(int x:p[now])cnt+=dfs(x);
return child[now]=cnt+;
}
void work(int now)
{
if(now!=)
vis[now]=vis[fa[now]]++(child[fa[now]]-child[now]-)/2.0;
for(int x:p[now])work(x);
}
int main()
{
int i,j,k,t;
scanf("%d",&n);
rep(i,,n)scanf("%d",&k),p[k].pb(i),fa[i]=k;
vis[]=1.0;
dfs();
work();
rep(i,,n)printf("%g ",vis[i]);
//system ("pause");
return ;
}
Puzzles的更多相关文章
- codeforces A. Puzzles 解题报告
题目链接:http://codeforces.com/problemset/problem/337/A 题意:有n个学生,m块puzzles,选出n块puzzles,但是需要满足这n块puzzles里 ...
- What are the 10 algorithms one must know in order to solve most algorithm challenges/puzzles?
QUESTION : What are the 10 algorithms one must know in order to solve most algorithm challenges/puzz ...
- C puzzles详解
题目:http://www.gowrikumar.com/c/ 参考:http://wangcong.org/blog/archives/291 http://www.cppblog.com/smag ...
- codeforces 377A. Puzzles 水题
A. Puzzles Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/problemset/problem/33 ...
- 【 POJ - 1204 Word Puzzles】(Trie+爆搜|AC自动机)
Word Puzzles Time Limit: 5000MS Memory Limit: 65536K Total Submissions: 10782 Accepted: 4076 Special ...
- 《algorithm puzzles》——谜题
这篇文章开始正式<algorithm puzzles>一书中的解谜之旅了! 狼羊菜过河: 谜题:一个人在河边,带着一匹狼.一只羊.一颗卷心菜.他需要用船将这三样东西运至对岸,然而,这艘船空 ...
- 《algorithm puzzles》——概述
这个专题我们开始对<algorithm puzzles>一书的学习,这本书是一本谜题集,包括一些数学与计算机起源性的古典命题和一些比较新颖的谜题,序章的几句话非常好,在这里做简单的摘录. ...
- [CF697D]Puzzles 树形dp/期望dp
Problem Puzzles 题目大意 给一棵树,dfs时随机等概率选择走子树,求期望时间戳. Solution 一个非常简单的树形dp?期望dp.推导出来转移式就非常简单了. 在经过分析以后,我们 ...
- [cf contest697] D - Puzzles
[cf contest697] D - Puzzles time limit per test 1 second memory limit per test 256 megabytes input s ...
随机推荐
- vc里面怎样实现对话框之间传递变量的值
Dialog1的类名是CDialog1, 头文件是dialog1.h.里有成员变量CString str1, str2;Dialog2的类名是CDialog2, 头文件是dialog2.h.里有成员变 ...
- java字符串格式化
转自:JAVA字符串格式化-String.format()的使用(转) 常规类型的格式化 String类的format()方法用于创建格式化的字符串以及连接多个字符串对象.熟悉C语言的同学应该记得C语 ...
- RESTful架构2--架构详解
转自:RESTful架构详解 1. 什么是REST REST全称是Representational State Transfer,中文意思是表述(编者注:通常译为表征)性状态转移. 它首次出现在200 ...
- Cv图像处理
http://wiki.opencv.org.cn/index.php/Cv%E5%9B%BE%E5%83%8F%E5%A4%84%E7%90%86 看看知识点,虽然是C 版本.
- Android实现Excel表格,且表格能左右、上下滑动
1.自定义实现一个水平滚动控件HorizontalScrollView import android.content.Context; import android.util.AttributeSet ...
- A - 娜娜梦游仙境系列——诡异的钢琴
A - 娜娜梦游仙境系列——诡异的钢琴 Time Limit: 2000/1000MS (Java/Others) Memory Limit: 128000/64000KB (Java/Othe ...
- 客户端 HttpUtils.java
package com.http.post; import java.io.ByteArrayOutputStream; import java.io.IOException; import java ...
- textarea内容太多, 鼠标点击全部显示
strRight+="<td bordercolor='#DEDEDE' width='500px' height='50'><div title='"+data ...
- to_date()与to_char()
1.以时间(Date类型)为查询条件时,可以用to_date函数实现: select t.* from D101 t where t.d101_40 = to_date('2013/9/12', 'y ...
- Inno Setup入门(十七)——Inno Setup类参考(3)
分类: Install Setup 2013-02-02 11:28 433人阅读 评论(0) 收藏 举报 标签 标签(Label)是用来显示文本的主要组件之一,也是窗口应用程序中最常用的组件之一,通 ...