Example 1:  
Input: words = ["a", "ab", "abc", "abcd", "abcde"]  
Output: 5  
Explanation: 
The longest chain is ["a", "ab", "abc", "abcd", "abcde"].  
Each word in the chain is formed by adding exactly one character to the previous word.

Example 2:  
Input: words = ["dog", "dogs", "dots", "dot", "d", "do"]  
Output: 4  
Explanation:  
The longest chain is ["d", "do", "dot", "dots"].  
Each word is formed by inserting one character into the previous word.

Disclaimer: Here is the practice link to help you assess your knowledge better. It's highly recommend trying to solve it before looking at the solution.

Approach

Algorithm

First, sort the words by their length in ascending order. This ensures that when processing a word, all possible shorter predecessors have already been considered.
For each word, generate all possible predecessors by removing one character at a time. This helps in identifying valid chains that can be formed by appending one character to an existing word.
Check if any of the generated predecessors exist in the set of already processed words. If a valid predecessor is found, this means the current word can extend the chain of the predecessor.
Use dynamic programming to store and update the longest chain length ending at each word. The length of the chain for the current word is updated based on the chain length of its valid predecessors plus one.
Keep track of the maximum chain length found during the iteration through the words. This value will represent the length of the longest word chain.

Code