HDU 4576 Robot （很水的概率题）

Robot

Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 102400/102400 K (Java/Others)
Total Submission(s): 158    Accepted Submission(s): 46

Problem Description

Michael has a telecontrol robot. One day he put the robot on a loop with n cells. The cells are numbered from 1 to n clockwise.



At first the robot is in cell 1. Then Michael uses a remote control to send m commands to the robot. A command will make the robot walk some distance. Unfortunately the direction part on the remote control is broken, so for every command the robot will chose a direction(clockwise or anticlockwise) randomly with equal possibility, and then walk w cells forward.
Michael wants to know the possibility of the robot stopping in the cell that cell number >= l and <= r after m commands.

 

 

Input

There are multiple test cases. 
Each test case contains several lines.
The first line contains four integers: above mentioned n(1≤n≤200) ,m(0≤m≤1,000,000),l,r(1≤l≤r≤n).
Then m lines follow, each representing a command. A command is a integer w(1≤w≤100) representing the cell length the robot will walk for this command.  
The input end with n=0,m=0,l=0,r=0. You should not process this test case.

 

 

Output

For each test case in the input, you should output a line with the expected possibility. Output should be round to 4 digits after decimal points.

 

 

Sample Input

3 1 1 2 1 5 2 4 4 1 2 0 0 0 0

 

 

Sample Output

0.5000 0.2500

 

 

Source

2013ACM-ICPC杭州赛区全国邀请赛

 

 

 

 

 

按照概率DP过去，比较暴力，T_T

 

 1 /* **********************************************
 2 Author      : kuangbin
 3 Created Time: 2013/8/10 11:51:05
 4 File Name   : F:\2013ACM练习\比赛练习\2013杭州邀请赛重现\1001.cpp
 5 *********************************************** */
 6 
 7 #include 
 8 #include <string.h>
 9 #include 
10 #include 
11 #include 
12 #include 
13 #include <set>
14 #include