THis is from Challenges-Mathematics section.Can u please tell me why its failing for test case 2 and 3

#1

#include
#include
#include
#define ll long long
using namespace std;

ll getC(ll N,ll R){
if(R>N-R)
R=N-R;
if(R==0)
return 1;
ll Num=1;
ll Den=1;
while® {
Num*=N;
Den*=R;
ll dvsr=__gcd(Num,Den);
Num/=dvsr;
Den/=dvsr;
N–;
R–;
}
return Num;
}
int main() {

int t;
cin>>t;
ll inp[t][2];
for(int i=0;i<t;i++)
	cin>>inp[i][0]>>inp[i][1];
for(int i=0;i<t;i++)
	if( inp[i][0]==inp[i][1])
	cout<<"1"<<endl;
	else if(inp[i][0] < inp[i][1])
	cout<<"0"<<endl;
	else 
	cout<<getC(inp[i][0]-1,inp[i][1]-1)<<endl;
return 0;

}

#2

@shellcodingblock Ans for this will be n+k-1C k-1

#3

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