if(a[i]<k){
       ans+=k-a[i];
        }
        else{
       ans1+=a[i]-k;
        }

I think that this problem is easy enough to try to make the solution as efficient as possible.

My consideration notes:
1. You can make it without using arrays, because the local information that you get is enough to generate the answer.
2. I think that it is worth trying to make the speaking variable names. It will certainly require additional time, but I think, it should pay off in the future.

Any good book (about Pascal for example) will tell about it

Ho do they get 0.001 seconds?