LeetCode - Unique Substrings in Wraparound String

Question Definition

Consider the string s to be the infinite wraparound string of “abcdefghijklmnopqrstuvwxyz”, so s will look like this: “…zabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcd….”.

Now we have another string p. Your job is to find out how many unique non-empty substrings of p are present in s. In particular, your input is the string p and you need to output the number of different non-empty substrings of p in the string s.

Note: p consists of only lowercase English letters and the size of p might be over 10000.

Example 1:

Input: "a"
Output: 1

Explanation: Only the substring "a" of string "a" is in the string s.

Example 2:

Input: "cac"
Output: 2
Explanation: There are two substrings "a", "c" of string "cac" in the string s.

Example 3:

Input: "zab"
Output: 6
Explanation: There are six substrings "z", "a", "b", "za", "ab", "zab" of string "zab" in the string s.

Java Solution

public int findSubstringInWraproundString(String p) {
    int[] cnt = new int[26];
    int len = 0;
    for (int i = 0; i < p.length(); ++i) {
        if (i > 0 && (p.charAt(i) == p.charAt(i - 1) + 1 || p.charAt(i - 1) - p.charAt(i) == 25)) {
            ++len;
        } else {
            len = 1;
        }
        cnt[p.charAt(i) - 'a'] = Math.max(cnt[p.charAt(i) - 'a'], len);
    }
    int result = 0;
    for(int count : cnt)
        result += count;
    return result;
}