一个小程序
int main(){ const int MOD = 1000000; int i, j, n; int S = 0; scanf("%d", &n); for(i = 1; i <= n; i++) { int factorial = 1; for(j = 1; j <= i; j++) factorial = factorial * j ; S += factorial; } printf("%d\n", S % MOD); return 0;}