- Difficulty: Hard
- Tags: LeetCode, Hard, String, Binary Search, String Matching, Suffix Array, Hash Function, Rolling Hash, leetcode-2223, O(n), Z-Function
Problem
You are building a string s
of length n
one character at a time, prepending each new character to the front of the string. The strings are labeled from 1
to n
, where the string with length i
is labeled si
.
- For example, for
s = "abaca"
,s1 == "a"
,s2 == "ca"
,s3 == "aca"
, etc.
The score of si
is the length of the longest common prefix between si
and sn
(Note that s == sn
).
Given the final string s
, return the sum of the score of every si
.
Example 1:
Input: s = "babab" Output: 9 Explanation: For s1 == "b", the longest common prefix is "b" which has a score of 1. For s2 == "ab", there is no common prefix so the score is 0. For s3 == "bab", the longest common prefix is "bab" which has a score of 3. For s4 == "abab", there is no common prefix so the score is 0. For s5 == "babab", the longest common prefix is "babab" which has a score of 5. The sum of the scores is 1 + 0 + 3 + 0 + 5 = 9, so we return 9.
Example 2:
Input: s = "azbazbzaz" Output: 14 Explanation: For s2 == "az", the longest common prefix is "az" which has a score of 2. For s6 == "azbzaz", the longest common prefix is "azb" which has a score of 3. For s9 == "azbazbzaz", the longest common prefix is "azbazbzaz" which has a score of 9. For all other si, the score is 0. The sum of the scores is 2 + 3 + 9 = 14, so we return 14.
Constraints:
1 <= s.length <= 105
s
consists of lowercase English letters.