题目:
![](https://img.laitimes.com/img/_0nNw4CM6IyYiwiM6ICdiwiI0gTMx81dsQWZ4lmZf1GLlpXazVmcvwFciV2dsQXYtJ3bm9CX9s2RkBnVHFmb1clWvB3MaVnRtp1XlBXe0xCMy81dvRWYoNHLwEzX5xCMx8FesU2cfdGLwMzX0xiRGZkRGZ0Xy9GbvNGLpZTY1EmMZVDUSFTU4VFRR9Fd4VGdsYTMfVmepNHLrJXYtJXZ0F2dvwVZnFWbp1zczV2YvJHctM3cv1Ce-cmbw5iM5YDOxImZiFTYlFTNihjNzYzX0UDNzUTM3AzLcFTMyIDMy8CXn9Gbi9CXzV2Zh1WavwVbvNmLvR3YxUjLyM3Lc9CX6MHc0RHaiojIsJye.png)
#include <bits/stdc++.h>
using namespace std;
long long mod=1e9+7;
int c[2005][2005];
int main()
{
for(int i=0;i<=2000;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;
}
}
int t;
cin>>t;
while(t--)
{
int a,b;
cin>>a>>b;
cout<<c[a][b]<<endl;
}
return 0;
}