CareerCup

we use array implementation but along with the array we will have an bit array of size size which is useful for deletion, we does not delete any element we just overwrite it, once delete command is executed for an element we set its' bit to zero.
and it is easy to implement array in circular faction as required by question.

I think a simple Array and a int location would be good
Whenever a new item come in, location++;
if location==size;location =0;

Array for storage of data. With index i pointing to index to be filled for new data. i will be incremented by formula i = (i+1)%SIZE_OF_ARRAY
As well as HASHTABLE<data,index> for constant time access to data.

class cache
{
Object[] elements;
int max;
int count;

cache(int i)
{
elements = new Object[i];
this.max=i;
}
void add(object obj)
{
if(count==max)
{
count=0;
}
element[count]=obj;
count++;
}

Object get(int i)
{
return element[i];
}
}

I think we can use cirsular linkedlist [This develops circular cache]+ Hashset [This provides random acess to cache]

Hashmap. With the position/index being the key and the data being the value.
ex {(1,3),(2,6)} ; here data 3 is inserted first , 6 second and so on. Just check the key in the hash map.