Largest Lexicographical Substring

Problem Overview

• Find the lexicographically largest substring of B that is a superstring of A (contains all characters of A, order ignored); if none exists, return -1.
• Input: two strings A and B; Output: the qualifying substring or -1; constraints unspecified.
• Relevant to string processing and text validation where coverage of required characters within a substring matters.
• This coding interview problem is known from Google interviews and is a common interview question.