![]() |
||||||||||
|
||||||||||
RobotTime Limit: 8000/4000 MS (Java/Others) Memory Limit: 102400/102400 K (Java/Others)Total Submission(s): 10011 Accepted Submission(s): 2802 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
Sample Output
Source | ||||||||||
|