Find Last Character

Problem Overview

• Find the last remaining character after repeatedly deleting every other character, alternating starts from the first and last positions.
• Input: alphanumeric string S (may include '$', '#', '&', '*') and integer K; form a new string by repeating S K times.
• Output: the single-character string that survives; constraints are unspecified.
• String-processing elimination problem for coding interview practice.
• Asked in Google interviews; a classic interview question.