Given two arrays sorted in ascending order, find the absolute minimum difference between any pair of elements |a-b| such that a is from one array and b is from another array.

For example consider the following two arrays.

array1 = [3, 27, 45, 68, 70, 81, 99]

array2 = [9, 16, 25, 35, 70, 84]

The minimum difference is

**2**(27-25).This can be calculated using the following algorithm.

- Take two indices i, j which point to the beginning of the two arrays (i.e 0)
- Take variable MinDiff and assign it the maximum possible value
- If array1[i] and array2[j] are equal return 0
- Otherwise update MinDiff if abs( array1[i] – array2[j] ) is the new minimum.
- If array1[i] > array2[j] move second index(j) forward otherwise move first index (i) forward.
- Repeat the above procedure until we reach the end of any of the two arrays.
- Finally process the remaining part of left-over array to update MinDiff.

This algorithm takes linear time – O(n) and constant space O(1). Here is the Java implementation of the above algorithm.