View Compilation Error

0_0_25714770_20556.cpp: In function 'int main()':
0_0_25714770_20556.cpp:8:36: error: 'a' was not declared in this scope
   for(int i=0;i<n;i++) scanf("%lf",a[i]),gl+=a[i];
                                    ^
0_0_25714770_20556.cpp:13:26: error: 'a' was not declared in this scope
     if(!(i&(1<<j))) sum+=a[j]*dp[i|(1<<j)],s+=a[j];
                          ^
0_0_25714770_20556.cpp:13:31: error: 'dp' was not declared in this scope
     if(!(i&(1<<j))) sum+=a[j]*dp[i|(1<<j)],s+=a[j];
                               ^