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FACTMODP - Factorial Modulo Prime |
Find $N!$ modulo $P$.
Input
The first line contains $T$ ($1 \le T \le 100,000$), the number of test cases.
Each of the next $T$ lines contains two integers $N$ ($0 \le N \le 10^{11}$) and $P$ ($2 \le P \le 10^{11}$), where $P$ is a prime.
Output
For each $N$ and $P$, output $N!$ modulo $P$.
Constraints
For each input file, It is guaranteed that (the sum of $\sqrt{P}) \le 320000$.
Example
Input
3 1000 9907 1000000 9999907 10000000000 99999999907
Output
4494 3354924 40583077821
Note
- Probably, $O(P)$ solutions will not pass.
- Intended solutions have a complexity of about $O(\sqrt{P} \log{P})$
- My solution runs in 0.5 seconds for each input file.
Added by: | Min_25 |
Date: | 2017-10-20 |
Time limit: | 10s-15s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All |
hide comments
2017-11-09 14:37:42 Min_25
@Michael Kharitonov Yes, to be exact, we need the complexity you wrote for the polynomial multiplication in Z/PZ. In this problem, the factor O(log P) is disregarded because it might be confusing. As for the polynomial interpolation, the tag might be misleading; intended solutions do not use it explicitly. Last edit: 2017-11-09 14:45:24 |
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2017-11-09 13:22:52 Michael Kharitonov
Let M(n) be the time to multiply 2 polynomials of degree n in Z/PZ. Then M(n)~n*log(n)*log(nP) Let I(n) be the time for polynomial interpolation of size n. Then I(n)~M(n)*log(n). I got complexity ~sqrt(P)*(log(P)^3). Where did I gain 2 extra logs? P.S. got rid of log(n) in interpolation. Last edit: 2017-11-12 01:38:14 |