1332 - Zoo
Time Limit : 1 Second
Memory Limit : 128 MB
Submission: 23
Solved: 15
- Description
- There are two famous Zoo(Ningbo-Zoo and Wuhan-Zoo) in the Country.When new animals come.They will be sent to Ningbo-Zoo in a probability of A( 0<=A<=1 ) and sent to Wuhan-Zoo in the a probability of 1-A .Unfortunately we don't know what A equals to . What we only know is that the K of the first N animals were sent to the Ningbo-Zoo.
Please find the expectation of the number of the next N animals that will be sent to the Ningbo-Zoo. - Input
- Input have multiple test cases and terminates with EOF.
Each case has a line containing two integers N(0＜N＜＝100000), K(0＜＝K＜＝N).
- Output
- For each case output one number indicating the expectation in one line rounded to the thousands.
- sample input
-
10 5 100 0
- sample output
-
5.000 0.980 HINT Animails are sent to each Zoo independently.
- hint
- source
- Haimiao Ding