题目描述
Problem Statement
Today, Snuke will eat B pieces of black chocolate and W pieces of white chocolate for an afternoon snack.
He will repeat the following procedure until there is no piece left:
- Choose black or white with equal probability, and eat a piece of that color if it exists.
For each integer i from 1 to B+W (inclusive), find the probability that the color of the i-th piece to be eaten is black.
It can be shown that these probabilities are rational, and we ask you to print them modulo 10^9 + 7, as described in Notes.
Input
Input is given from Standard Input in the following format:
B W
Output
Print the answers in B+W lines. In the i-th line, print the probability that the color of the i-th piece to be eaten is black, modulo 10^{9}+7.
Constraints
- All values in input are integers.
- $1 \leq B,W \leq 10^{5}$
Sample Input 1
2 1
Sample Output 1
500000004
750000006
750000006
- There are three possible orders in which Snuke eats the pieces:
- white, black, black
- black, white, black
-
black, black, white
-
with probabilities $\frac{1}{2}, \frac{1}{4}, \frac{1}{4},$ respectively. Thus, the probabilities of eating a black piece first, second and third are $\frac{1}{2},\frac{3}{4}$ and $\frac{3}{4},$ respectively.
Sample Input 2
3 2
Sample Output 2
500000004
500000004
625000005
187500002
187500002
- They are $\frac{1}{2},\frac{1}{2},\frac{5}{8},\frac{11}{16}$ and $\frac{11}{16},$ respectively.
Sample Input 3
6 9
Sample Output 3
500000004
500000004
500000004
500000004
500000004
500000004
929687507
218750002
224609377
303710940
633300786
694091802
172485353
411682132
411682132
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分