Given a string s, return the last substring of s in lexicographical order (this is always the suffix starting at the position of the lexicographically largest rotation start).
Input: A quoted string s.
Output: Quoted string — the lexicographically last substring.
Input: "abab"
Output: "bab"
Explanation: 'bab' is the largest suffix.Input: "leetcode"
Output: "tcode"
Explanation: Largest suffix.Input: "a"
Output: "a"
Explanation: Single char.1<=s.length<=4*10^5