Count the Number of String Pairs With No Common Characters

Given a list of strings words, count the number of distinct unordered pairs of indices (i, j) with i < j such that the two strings share no common characters. Count index pairs (even if two strings have the same content, different positions are treated as different elements). Requirement: aim for a solution close to O(n log n) as requested by the interviewer. Example Input: ["apple", "banana", "peach", "kiwi"] Output: 3 Explanation: valid pairs are: ("apple", "kiwi") ("banana", "kiwi") ("peach", "kiwi") Constraints (can be clarified/assumed during the interview) 1 <= n <= 2e5 (discussion acceptable) Character set: assume lowercase a-z (otherwise discuss bitsets/hashing) Return the count. Example Input apple banana peach kiwi Output 3