SHOWING WRONG ANSWER ON TWO TEST CASES
i have used a * b / d = ((a / d) * b) + (((a % d) * b) / d)
#include<bits/stdc++.h>
using namespace std;
typedef unsigned long long int ll;
ll INF=1e18;
int main()
{
int t;
cin>>t;
while(t–)
{
ll n,k;
cin>>n>>k;
ll nn=n;
n=n-1;
ll sum=1;
int j=min(k-1,n-k+1);
for(ll i=0;i<j;i++)
{
sum=(sum/(i+1))(n-i)+((sum%(i+1))(n-i))/(i+1);
}
if(nn<k)
sum=0;
cout<<sum<<endl;
}
}