Longest String Chain Coding Problem Solution

“Longest String Chain” is a popular interview problem because it looks like a simple word puzzle, but it quietly tests whether you can combine sorting, dynamic programming, and careful comparisons. You’re given a list of words, and your task is to determine the length of the longest possible chain where each word is formed by adding exactly one character to the previous word. A word A is considered a predecessor of word B if you can insert one letter anywhere in A , without changing the order of existing letters, to create B . This rule preserves the original sequence of characters while allowing exactly one additional character to appear. For example, the sequence "a" → "ab" → "abc" forms a valid chain because each step adds one character while keeping the original letters in the same order. Similarly, "cat" → "coat" is valid because you can insert the letter 'o' without rearranging the other characters. However, "ab" → "ba" is not valid because the characters change order rather than