题目描述
You are using at most A number of 1s and at most B number of 2s. How many different evaluation results are possible when they are formed in an expression containing only addition + sign and multiplication * sign are allowed?
Note that, multiplication takes precedence over addition.
For example, if A=2 and B=2, then we have the following expressions:
1, 11 = 1
2, 12, 112, 1+1 = 2
1+2, 1+12 = 3
2+2, 22, 1+1+2, 122, 1122, 12+12, 112+2, 12+2 = 4
1+2+2, 1+12+2 = 5
1+1+2+2, 1+1+22 = 6
So there are 6 unique results that can be formed if A = 2 and B = 2.
Input Format
The first line contains the number of test cases T, T testcases follow each in a newline.
Each testcase contains 2 integers A and B separated by a single space.
Constraints
1 <= T <= 10^{5}
0<=A<=1000000000
0<=B<=1000
Output Format
Print the number of different evaluations modulo (%) (10^{9}+7.)
Sample Input
4
0 0
2 2
0 2
2 0
Sample Output
0
6
2
2
Explanation
When A = 0, B = 0, there are no expressions, hence 0.
When A = 2, B = 2, as explained in the problem statement above, expressions leads to 6 possible solutions.
When A = 0, B = 2, we have 2, 2+2 or 22, hence 2.
When A = 2, B = 0, we have 1 or 11, 1+1 hence 2.
输入格式
见题面
输出格式
见题面