Oz's new problem
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3.8 (49 votes)
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Combinatorics
Hard
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Mathematics
Problem
2% Success 96 Attempts 50 Points 5s Time Limit 256MB Memory 1024 KB Max Code
Today Oz has an interesting problem for you. Oz has a set of M balls numbered from 0 to M-1. He has removed X balls from the set and calculated the sum of the numbers of removed balls. He has given you a hint that the sum is divisible by M.
Now your task is to count the number of ways of removing X balls. Output the answer modulo 109+7.
Input:
First line contains one integer T - number of test cases.
Each test case contains two space separated integers M and X.
Output:
For each test case output the desired answer modulo 109+7.
Constraints:
1 ≤ T ≤ 10
1 ≤ M ≤ 109
1 ≤ X ≤ 105
X ≤ M
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