Say you have two large files (100 TB each) and only 1 MB of RAM. What's an efficient algorithm that will print the missing lines (diff)? The files don't necessarily contain duplicates.
The two files are not sorted and could have different ordering in both files.
File1 File2 A B B A C C D E F D F Output: File 2: E
The input are two large files (containing strings).
The output is a list of strings telling you the presence of a line in File X and not in File Y.