Given a string s, consider all duplicated substrings: (contiguous) substrings of s that occur 2 or more times. The occurrences may overlap. Return any duplicated substring that has the longest possible length. If s does not have a duplicated substring, the answer is "". Example 1: Input: s = "banana" Output: "ana" Example 2: Input: s = "abcd" Output: "" Constraints: 2 <= s.length <= 3 * 104 s consists of lowercase English letters.