Describe in English the idea of your algorithm, define the memo table, write the base case and the recursive step to fill the table, and analyze the run time. No need for pseudo code.

Given two strings of length n and m, design an algorithm that outputs the length of the longest common substring of the two strings. If A[1, . . . n] is the array representing a string, then any contiguous chunk A[i, . . . , j] is a substring of A.