## Problem Determine whether an abbreviation validly represents a word. An abbreviation contains lowercase letters and positive decimal numbers. A number means “skip this many characters” in the word. Letters must match the next unskipped word character exactly. A numeric token may not start with `0`. Both the word and abbreviation must be consumed completely. ### Function Contract Implement `isValidWordAbbreviation(word, abbreviation)` and return a Boolean. ### Constraints & Assumptions - `1 <= len(word) <= 100,000`. - `0 <= len(abbreviation) <= 100,000`. - `word` contains lowercase English letters. - `abbreviation` contains lowercase English letters and digits. - A multi-digit number is parsed as one skip count. - Skip counts may be larger than the remaining word length; that makes the abbreviation invalid. ### Clarifying Questions to Ask - Is zero a legal skip? No, so any numeric token beginning with `0` is invalid. - Are adjacent digits one number? Yes. - Must letter comparison be case-sensitive? Inputs are lowercase and matching is exact. - Is an empty abbreviation valid for a nonempty word? No. ```hint Advance two pointers with two token types On a letter, compare and advance both pointers by one. On a digit, parse the complete number and advance only the word pointer by that count. ``` ### Examples - `word = "internationalization"`, `abbreviation = "i18n"` returns `true`. - `word = "substitution"`, `abbreviation = "s10n"` returns `false`. - `word = "apple"`, `abbreviation = "a3e"` returns `true`. - `word = "apple"`, `abbreviation = "a03e"` returns `false`. - `word = "word"`, `abbreviation = "5"` returns `false`. ### Evaluation Focus - Rejects leading zeroes, oversize skips, mismatched letters, and partial consumption. - Parses long numeric tokens without integer overflow by stopping once the skip exceeds the remaining length. - Runs in `O(len(word) + len(abbreviation))` time and `O(1)` auxiliary space. ### Extensions to Discuss 1. How would literal digits inside the word be escaped? 2. Can the parser report the first failing abbreviation index? 3. How would wildcard letters differ from numeric skips?