longest-duplicate-substring

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1044. Longest Duplicate Substring (Hard)

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.

Related Topics

[String] [Binary Search] [Sliding Window] [Rolling Hash] [Suffix Array] [Hash Function]

Hints

Hint 1

Binary search for the length of the answer. (If there's an answer of length 10, then there are answers of length 9, 8, 7, ...)

Hint 2

To check whether an answer of length K exists, we can use Rabin-Karp 's algorithm.