Word Ladder

Statement

Given two words, src and dest, and a list, words, return the number of words in the shortest transformation sequence from src to dest. If no such sequence can be formed, return $0$.

A transformation sequence is a sequence of words $($src $\to$ $word_1$ $\to$ $word_2$ $\to$ $word_3$ $...$ $\to$ $word_j$ $)$ that has the following properties:

• $word_j =$ dest
• Every pair of consecutive words differs by a single character.
• All the words in the sequence are present in the words. The src does not need to be present in words.

Constraints:

• $1 \leq$ src.length $\leq 10$

• src.length $=$ dest.length $=$ words[i].length

• src $\neq$ dest

• $1 \leq$ words.length $\leq 5000$

• No duplicates in the words

• src, dest, and words[i] consist of lowercase English characters.

Examples