#include <iostream> using namespace std; const int maxn=50; const int y=2009; int main( ) { int n,c[maxn][maxn],i,j,s=0; cin >> n; c[0][0]=1; for(i=1;i<=n;i++) { c[i][0]=1; for(j=1;j<i;j++) c[i][j]=c[i-1][j-1]+c[i-1][j]; c[i][i]=1; } for(i=0;i<=n;i++) s=(s+c[n][i])%y; cout << s << endl; return 0; }输入:17
输出:1