RNG - Random Number Generator
LoadingTime got a RNG (Random Number Generator) from his classmate several weeks ago. And he spent a lot of time study it. He found that RNG can generate a real number in range [-S, S] by executing following steps. First RNG generates n integer X1 ... Xn, the sum of which is equal to S. Then for each Xi, it generates a real number in range [-Xi, Xi] randomly. The output (a real number) of RNG will be the sum of the N generated real numbers. LoadingTime noticed that the distribution of the output was very interesting, and he wanted to know: for given N and X, what's the probability that the generated number is in range [A, B]. Could you help him?
Input
The first line contains an integer T representing the number of test cases.
For each test case, the first line contains three integers N, A, B (1 ≤ N ≤ 10, -100 ≤ A ≤ B ≤ 100) In the second line of the test case, you are given X1 ... Xn (1 ≤ Xi ≤ 10).
Output
For each test case, print a line contains a real number representing the probability as the problem required. It must be printed with exactly nine decimal places.
Example
Input: 5 1 -100 100 10 1 10 90 10 1 -20 5 10 2 -20 5 5 5 5 -5 10 1 2 3 4 5 Output: 1.000000000 0.000000000 0.750000000 0.875000000 0.864720052
hide comments
[Trichromatic] XilinX:
2011-07-17 03:57:50
My Ac program uses all double!!! What a joke! |
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JFF:
2011-07-17 03:57:50
after using all variables long double, I finally got ac!!!! what a joke! |
Added by: | Bin Jin |
Date: | 2007-11-03 |
Time limit: | 1s |
Source limit: | 10000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: CPP |
Resource: | www.test-the-best.by |