Given two integers - n and r, your task is to calculate the
combinatorial nCr.
Implementation:
The first line - number of testcases T.
Then T lines follow, each containing two positive integers - n and r.
output
Print T lines, each line containing the value of nCr.
nCr = n! / r! (n-r)!
Implementation:
#include <stdio.h> unsigned long long int fact(unsigned long long int n) { if(n!=1) return n*fact(n-1); } int main() { unsigned long long int t,n,r,x,y,result; scanf("%llu",&t); while(t--) { scanf("%llu %llu",&n,&r); x=fact(r)*fact(n-r); y=fact(n); result=y/x; printf("%llu\n",(result%1000000007)); } return 0; }
Input
The first line - number of testcases T.
Then T lines follow, each containing two positive integers - n and r.
output
Print T lines, each line containing the value of nCr.
Sample Input
1
100 10
Sample Output
17310309456440