Word Ladder Leetcode Hard

# Aim

To solve the leetcode hard problem _"Word Ladder"_ in C++.
Given two words, beginWord and endWord, and a dictionary wordList, return the number of words in the shortest transformation sequence from beginWord to endWord, or 0 if no such sequence exists.
Admins please assign this to me under LGM SOC'21.

# Details
A transformation sequence from word beginWord to word endWord using a dictionary wordList is a sequence of words beginWord -> s1 -> s2 -> ... -> sk such that:
1. Every adjacent pair of words differs by a single letter.
2. Every si for 1 <= i <= k is in wordList. Note that beginWord does not need to be in wordList.
3. sk == endWord

### Programming language

- [ ] C
- [x] C++
- [x] Java
- [x] Python