Inspired by the Cody problem found here.
The Levenshtein distance is a charater-based string metric used to measure the difference between two strings (for details, look here). In this problem, you need to implement a word-based version of the Levenshtein distance.
Given two strings, compute the minimum number of word-edits to transform one string into another. The allowable edits are insertion, deletion, or substitution of a single word. Assume words are case-insensitive. Contractions and hyphenated words are allowed, but you may ignore other punctuation.
s1 = 'I do not like MATLAB' s2 = 'I love MATLAB a lot'
d = 4
because at least four edits are required to transform s1 into s2 (substitution on the last four words).