The Smallest Difference

Problem

Given two array of integers(the first array is array A, the second array is array B), now we are going to find a element in array A which is A[i], and another element in array B which is B[j], so that the difference between A[i] and B[j] (|A[i] - B[j]|) is as small as possible, return their smallest difference.

Example

For example, given array A = [3, 6, 7, 4], B = [2, 8, 9, 3], return 0.

Challenge

O(n log n) time.