动态规划子数组系列一＞环绕字符串中唯一的子字符串

 public int findSubstringInWraproundString(String ss) {
        int n =  ss.length();
        int[] dp = new int[n];
        char[] s = ss.toCharArray();
        for(int i = 0; i < n; i++) dp[i] = 1;
        for(int i = 1; i < n; i++){
            if(s[i - 1] + 1 == s[i] || (s[i - 1] == 'z' && s[i] == 'a'))
                dp[i] += dp[i-1];
        }

        //去重:把dp表中的字串重复的，只留最长的字串(hash表来建立映射关系)
        int[] hash = new int[26];
        for(int i = 0; i < n; i++)
            hash[s[i]-'a'] = Math.max(hash[s[i]-'a'], dp[i]);

  
        //返回
        int ret = 0;
        for(int x : hash)
            ret += x;

        return ret;
    }