1 #include 
     
       2 #include 
      
        3 int main() { 4     const int MOD = 1000000; 5     int n, s = 0; 6     //scanf("%d", &n); 7     n =10000000; 8     for (int i = 1; i <= n; i++) { 9         int factorial = 1;10         for (int j = 1; j <= i; j++)11             factorial = (factorial*j%MOD);12         s = (s + factorial) % MOD;13     }14     cout << s; 15     printf("Time used=%.2f\n", (double)clock() / CLOCKS_PER_SEC);16     17     return 0;18 }
      
     

clock()为计时函数，要引入<time.h>库 其功能为返回从程序运行开始到打印出的时间 除以常数CLOCKS_PRE_SEC后得到的值以秒为单位。