Question

Let’s say I have two strings:

"hello"
"love"

The size of the maximum subarray in the strings is 2: “lo”.

Here’s another example:

"ABBABBA"
"BBABCBA"
Maximum subarray: "BBAB"
Size: 4

Basically, how can I solve this problem in the most efficient way?

My idea is the following:

• Generate all subarrays for one string
• Generate all subarrays for the other string;
• Compare all subarrays
• The result is the size of the largest matching subarrays

But I think this is some bad-looking brute force. Any idea of how I can improve this?

Thank you!

EDIT
I’ll need the string too.

Answer 1

This is a well-known problem called Longest Common Substring. It can be solved in O(mn), where m and n are lengths of the individual strings, using dynamic programming approach. The article in Wikipedia contains easy-to-follow pseudocode.