besides compare one with all the elements in other array
You will have to compare A[] to B[] in order to know that they are the same -- unless you know a lot about what kind of data they can hold. The nature of the comparison probably has many solutions and can be optimized as required.
If the arrays are very strictly created ie only sequential values of a known pattern and always starts from a known point you could just look at the length of each array and know whether or not all items are common.
This unfortunately doesn't sound like a very realistic or useful array and so you are back to checking for A[i] in B[]
