Unique Substrings in Wraparound String

Problem

We define the string s to be the infinite wraparound string of "abcdefghijklmnopqrstuvwxyz", so s will look like this:

"...zabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcd....".

Given a string p, return **the number of *unique non-empty substrings* of p are present in **s.

Example 1:

Input: p = "a"
Output: 1
Explanation: Only the substring "a" of p is in s.

Example 2:

Input: p = "cac"
Output: 2
Explanation: There are two substrings ("a", "c") of p in s.

Example 3:

Input: p = "zab"
Output: 6
Explanation: There are six substrings ("z", "a", "b", "za", "ab", and "zab") of p in s.

Constraints:

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

Solution (Java)

class Solution {
    public int findSubstringInWraproundString(String p) {
        char[] str = p.toCharArray();
        int n = str.length;
        int[] map = new int[26];
        int len = 0;
        for (int i = 0; i < n; i++) {
            if (i > 0 && ((str[i - 1] + 1 == str[i]) || (str[i - 1] == 'z' && str[i] == 'a'))) {
                len += 1;
            } else {
                len = 1;
            }
            // we are storing the max len of string for each letter and then we will count all these
            // length.
            map[str[i] - 'a'] = Math.max(map[str[i] - 'a'], len);
        }
        int answer = 0;
        for (int num : map) {
            answer += num;
        }
        return answer;
    }
}

Explain:

nope.

Complexity:

Time complexity : O(n).
Space complexity : O(n).