Longest common prefix length of all substrings and a string

问题

I found similar questions on StackOverflow, but my question is different.

Given a string s contains lowercase alphabet. I want to find the length of Longest common Prefix of all substrings.

For example

s = 'ababac'

Then substrings are as follow:

1: s(1, 6) = ababac
2: s(2, 6) = babac
3: s(3, 6) = abac
4: s(4, 6) = bac
5: s(5, 6) = ac
6: s(6, 6) = c

Now, The lengths of LCP of all substrings are as follow

1: len(LCP(s(1, 6), s)) = 6 
2: len(LCP(s(2, 6), s)) = 0
3: len(LCP(s(3, 6), s)) = 3
4: len(LCP(s(4, 6), s)) = 0
5: len(LCP(s(5, 6), s)) = 1
6: len(LCP(s(6, 6), s)) = 0

I am using character by character matching

    string commonPrefix(string s1, string s2) { 
        int minlen = minlength1(s1, s2); 
        char current; 
        int result = 0;
        for (int i=0; i<minlen; i++) { 
            current = s1[i]; 
            for (int j=1 ; j<n; j++) 
                if (s2[i] != current) 
                return result; 
            result++;
        } 

        return result; 
    }

But still, it's O(n2). I know all substrings are overlapping on one another, It can be optimized further. Can anyone help to optimize this code?

来源：https://stackoverflow.com/questions/53574799/longest-common-prefix-length-of-all-substrings-and-a-string