Java: Count ways to increase LCS length of two Strings by one

Difficulty Level: MEDIUM

Problem Statement:

You are given two strings of lower alphabet characters, you need to find the number of ways to insert a character in the first string such that length of the Longest Common Subsequence (LCS) of both strings increases by one.

Input:

str1 = "efgefg"

str2 = "efgh"

Output:

4