1796. Second Largest Digit in a String

Problem

Given an alphanumeric string s, return **the *second largest* numerical digit that appears in s, or -1 if it does not exist**.

An alphanumeric** **string is a string consisting of lowercase English letters and digits.

  Example 1:

Input: s = "dfa12321afd"
Output: 2
Explanation: The digits that appear in s are [1, 2, 3]. The second largest digit is 2.

Example 2:

Input: s = "abc1111"
Output: -1
Explanation: The digits that appear in s are [1]. There is no second largest digit. 

  Constraints:

• 1 <= s.length <= 500

• s consists of only lowercase English letters and/or digits.

Solution (Java)

class Solution {
    public int secondHighest(String s) {
        int largest = -1;
        int sl = -1;
        for (char ch : s.toCharArray()) {
            if (Character.isDigit(ch)) {
                int n = ch - '0';
                if (n > largest) {
                    sl = largest;
                    largest = n;
                } else if (n > sl && n < largest) {
                    sl = n;
                }
            }
        }
        return sl;
    }
}

Explain:

nope.

Complexity:

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