View Compilation Error

0_0_39106166_27243.cpp: In function 'double compute()':
0_0_39106166_27243.cpp:30:25: error: 'a' was not declared in this scope
   30 |     for(int i = 0; i <= a[1]; ++i) D[i] = 1.0 / fac[i];
      |                         ^
0_0_39106166_27243.cpp:37:33: error: 'a' was not declared in this scope
   37 |             for(int k = 0; k <= a[i]; ++k)
      |                                 ^
0_0_39106166_27243.cpp: In function 'int main()':
0_0_39106166_27243.cpp:59:26: error: 'a' was not declared in this scope
   59 |             scanf("%d", &a[i]); // 每种物品的数量
      |                          ^