<p>Given a string <code>s</code>, return <em>the last substring of</em> <code>s</code> <em>in lexicographical order</em>.</p> <p> </p> <p><strong class="example">Example 1:</strong></p> <pre> <strong>Input:</strong> s = "abab" <strong>Output:</strong> "bab" <strong>Explanation:</strong> The substrings are ["a", "ab", "aba", "abab", "b", "ba", "bab"]. The lexicographically maximum substring is "bab". </pre> <p><strong class="example">Example 2:</strong></p> <pre> <strong>Input:</strong> s = "leetcode" <strong>Output:</strong> "tcode" </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= s.length <= 4 * 10<sup>5</sup></code></li> <li><code>s</code> contains only lowercase English letters.</li> </ul>