Next: compute "N choose R" modulo the same prime, for use in a binomial-probability example. Read N and R. Print C(N,R) mod (10^9+7) using precomputed factorials and modular inverse (Fermat's little theorem), not Pascal's triangle, since N can be large.
Input
Two integers N R.
Output
C(N,R) mod (10^9+7).
Constraints
0 ≤ R ≤ N ≤ 10^6
Sample Input
5 2
Sample Output
10
main.c
Loading editor…
Write C, then Run (custom I/O) or Submit (sample tests). ⌘/Ctrl+Enter submits.