#P15161. [SWERC 2022] Uniform Chemistry

[SWERC 2022] Uniform Chemistry

题目描述

In a parallel universe there are n n chemical elements, numbered from 1 1 to n n . The element number n n has not been discovered so far, and its discovery would be a pinnacle of research and would bring the person who does it eternal fame and the so-called SWERC prize.

There are m m independent researchers, numbered from 1 1 to m m , that are trying to discover it. Currently, the i i -th researcher has a sample of the element si s_i . Every year, each researcher independently does one fusion experiment. In a fusion experiment, if the researcher currently has a sample of element a a , they produce a sample of an element b b that is chosen uniformly at random between a+1 a+1 and n n , and they lose the sample of element a a . The elements discovered by different researchers or in different years are completely independent.

The first researcher to discover element n n will get the SWERC prize. If several researchers discover the element in the same year, they all get the prize. For each i=1,2,,m i = 1, \, 2, \, \dots, \, m , you need to compute the probability that the i i -th researcher wins the prize.

输入格式

The first line contains two integers n n and m m ( 2n100 2 \le n \le 100 , 1m10 1 \le m \le 10 ) — the number of elements and the number of researchers.

The second line contains m m integers s1,s2,,sm s_1, \, s_2, \, \dots, \, s_m ( 1si<n 1 \le s_i < n ) — the elements that the researchers currently have.

输出格式

Print m m floating-point numbers. The i i -th number should be the probability that the i i -th researcher wins the SWERC prize. Your answer is accepted if each number differs from the correct number by at most 108 10^{-8} .

2 3
1 1 1
1.0 1.0 1.0
3 3
1 1 2
0.5 0.5 1.0
3 3
1 1 1
0.625 0.625 0.625
100 7
1 2 4 8 16 32 64
0.178593469 0.179810455 0.182306771
0.187565366 0.199300430 0.229356322
0.348722518

提示

In the first sample, all researchers will discover element 2 2 in the first year and win the SWERC prize.

In the second sample, the last researcher will definitely discover element 3 3 in the first year and win the SWERC prize. The first two researchers have a 50% 50\% chance of discovering element 2 2 and a 50% 50\% chance of discovering element 3 3 , and only element 3 3 will bring them the prize.

In the third sample, each researcher has an independent 50% 50\% chance of discovering element 3 3 in the first year, in which case they definitely win the SWERC prize. Additionally, if they all discover element 2 2 in the first year, which is a 12.5% 12.5\% chance, then they will all discover element 3 3 in the second year and all win the prize.