编程介的小学生 2019-12-06 21:43 采纳率: 20.5%
浏览 79

Random Walking 怎么来写的

Problem Description
The Army of Coin-tossing Monkeys (ACM) is in the business of producing randomness. Good random numbers are important for many applications, such as cryptography, online gambling, randomized algorithms and panic attempts at solutions in the last few seconds of programming competitions.

Recently, one of the best monkeys has had to retire. However, before he left, he invented a new, cheaper way to generate randomness compared to directly using the randomness generated by coin-tossing monkeys. The method starts by taking an undirected graph with 2n nodes labelled 0, 1, …, 2n - 1. To generate k random n-bit numbers, they will let the monkeys toss n coins to decide where on the graph to start. This node number is the first number output. The monkeys will then pick a random edge from this node, and jump to the node that this edge connects to. This new node will be the second random number output. They will then select a random edge from this node (possibly back to the node they arrived from in the last step), follow it and output the number of the node they landed on. This walk will continue until k numbers have been output.

During experiments, the ACM has noticed that different graphs give different output distributions, some of them not very random. So, they have asked for your help testing the graphs to see if the randomness is of good enough quality to sell.

They consider a graph good if, for each of the n bits in each of the k numbers generated, the probability that this bit is output as 1 is greater than 25% and smaller than 75%.

Input
The input will consist of several data sets. Each set will start with a line consisting of three numbers k, n, e separated by single spaces, where k is the number of n-bit numbers to be generated and e is the number of edges in the graph (1 ≤ k ≤ 100, 1 ≤ n ≤ 10 and 1 ≤ e ≤ 2000). The next e lines will consist of two space-separated integers v1, v2 where 0 ≤ v1, v2 < 2n and v1 ≠ v2. Edges are undirected and each node is guaranteed to have at least one edge. There may be multiple edges between the same pair of nodes.
The last test case will be followed by a line with k = n = e = 0, which should not be processed.

Output
For each input case, output a single line consisting of the word Yes if the graph is good, and No otherwise.

Sample Input
10 2 3
0 3
1 3
2 3
5 2 4
0 1
0 3
1 2
2 3
0 0 0

Sample Output
No
Yes

  • 写回答

0条回答 默认 最新

    报告相同问题?

    悬赏问题

    • ¥15 安卓adb backup备份应用数据失败
    • ¥15 eclipse运行项目时遇到的问题
    • ¥15 关于#c##的问题:最近需要用CAT工具Trados进行一些开发
    • ¥15 南大pa1 小游戏没有界面,并且报了如下错误,尝试过换显卡驱动,但是好像不行
    • ¥15 没有证书,nginx怎么反向代理到只能接受https的公网网站
    • ¥50 成都蓉城足球俱乐部小程序抢票
    • ¥15 yolov7训练自己的数据集
    • ¥15 esp8266与51单片机连接问题(标签-单片机|关键词-串口)(相关搜索:51单片机|单片机|测试代码)
    • ¥15 电力市场出清matlab yalmip kkt 双层优化问题
    • ¥30 ros小车路径规划实现不了,如何解决?(操作系统-ubuntu)