Company: HashedIn_19sep
Difficulty: medium
Lexicographically Smallest Cleaned Message Problem Description In a secure communications system, each transmitted message is represented as a string of symbols (lowercase English letters). Due to interference, extra symbols may be embedded in the message. To improve clarity, exactly k symbols must be removed from the received message while keeping the remaining symbols in their original order. In addition, regulatory guidelines require that no two adjacent symbols in the cleaned message are identical. Your task is to determine, among all possible subsequences (formed by removing exactly k characters from the original message) that satisfy the condition of having no consecutive identical symbols, the lexicographically smallest one. If no valid cleaned message exists, output -1. Input Variables S (string): A string of lowercase English letters representing the received message. Its length n satisfies 1 ≤ n ≤ 100000. k (integer): The exact number of characters to remove from S. It satisf