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