distinct-echo-substrings

< Previous 　　　　　　　　　　　　　　　　 Next >

1316. Distinct Echo Substrings (Hard)

Return the number of distinct non-empty substrings of text that can be written as the concatenation of some string with itself (i.e. it can be written as a + a where a is some string).

 

Example 1:

Input: text = "abcabcabc"
Output: 3
Explanation: The 3 substrings are "abcabc", "bcabca" and "cabcab".

Example 2:

Input: text = "leetcodeleetcode"
Output: 2
Explanation: The 2 substrings are "ee" and "leetcodeleetcode".

 

Constraints:

• 1 <= text.length <= 2000
• text has only lowercase English letters.

Related Topics

[Trie] [String] [Dynamic Programming] [Sliding Window] [Hash Function] [Rolling Hash]

Hints

Hint 1

Given a substring of the text, how to check if it can be written as the concatenation of a string with itself ?

Hint 2

We can do that in linear time, a faster way is to use hashing.

Hint 3

Try all substrings and use hashing to check them.