problem1044

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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: "banana"
Output: "ana"

Example 2:

Input: "abcd"
Output: ""

 

Note:

1. 2 <= S.length <= 10^5
2. S consists of lowercase English letters.

Related Topics

[Hash Table] [Binary Search]

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.