题解

#include <bits/stdc++.h>
using namespace std;
int n,r,s[105][105];
int main(){	
	cin>>n>>r;
	for (int i=1;i<=n;i++) s[i][1] = 1;
	for (int i=1;i<=n;i++) s[i][i] = 1;
	
	for (int i=2;i<=n;i++){
		for (int j=2;j<=n;j++){
			s[i][j] = (j*s[i-1][j]+s[i-1][j-1])%10007;
		}
	}
	cout<<s[n][r];
	return 0;
}