1044. Longest Duplicate Substring

https://leetcode.com/problems/longest-duplicate-substring

Description

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.

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