进阶 Day 2
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 2010, MOD = 1e9 + 7;
int n;
int C[N][N];
void init()
{
for (int i = 0; i < N; i++)
for (int j = 0; j <= i; j++)
if(!j) C[i][j] = 1;
else C[i][j] = (C[i - 1][j - 1] + C[i - 1][j]) % MOD;
} //init
int main(void)
{
init();
scanf("%d", &n);
while (n--)
{
int a, b;
scanf("%d%d", &a, &b);
int res = C[a][b];
printf("%d\n", res);
}
return 0;
}