LA 5092 Permutation Counting

#include<cstdio>#include<cstring>#define MOD 1000000007using namespace std;long long dp[1060][1060];void init(){dp[1][0]=1;dp[1][1]=0;for(int i=2;i<=1000;i++)for(int j=0;j<i;j++){dp[i][j]=(dp[i-1][j]*(j+1)%MOD+dp[i-1][j-1]*(i-j)%MOD)%MOD; }} int main(){init();int n,k;while(~scanf("%d%d",&n,&k)){printf("%lld\n",dp[n][k]);}}