Give the algorithm and define the Subproblems in this case and do a also do the runtime analysis of the algorithm

Given two strings r 122 an and y yiy2.- ym, we wish to find the length of their longest common substring, that is, the largest k for which there are indices i and j with Give an algorithm that outputs the positions i and j where the longest common substring starts in each of the strings, and the length k of this longest common substring