LeetCode [1062] Longest Repeating Substring

 1062. Longest Repeating Substring

Medium

Given a string S, find out the length of the longest repeating substring(s). Return 0 if no repeating substring exists.

 

Example 1:

Input: S = "abcd"
Output: 0
Explanation: There is no repeating substring.

Example 2:

Input: S = "abbaba"
Output: 2
Explanation: The longest repeating substrings are "ab" and "ba", each of which occurs twice.

Example 3:

Input: S = "aabcaabdaab"
Output: 3
Explanation: The longest repeating substring is "aab", which occurs 3 times.

Example 4:

Input: S = "aaaaa"
Output: 4
Explanation: The longest repeating substring is "aaaa", which occurs twice.

 

Constraints:

• The string S consists of only lowercase English letters from 'a' - 'z'.
• 1 <= S.length <= 1500

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class Solution { public int longestRepeatingSubstring(String S) { int n = S.length(); int dp[][] = new int[n][n]; int ret = 0; for(int i=0; i<n; ++i){ for(int j=i+1; j<n; ++j){ if(S.charAt(i)==S.charAt(j)){ if(i==0 || j==0){ dp[i][j] = 1; }else{ dp[i][j] = dp[i-1][j-1]+1; } ret = Math.max(ret, dp[i][j]); } } } return ret; } }