SecondLargestDigitInAString.cpp

// Source : https://leetcode.com/problems/second-largest-digit-in-a-string/
// Author : Hao Chen
// Date   : 2021-03-22

/***************************************************************************************************** 
 *
 * 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.
 ******************************************************************************************************/

class Solution {
public:
    int secondHighest(string s) {
        int first = -1, second = -1;
        for (auto& c : s){
            if (c >='0' && c<='9') {
                int n = c - '0';
                if ( n > first) {
                    second = first;
                    first = n;
                }else if (n < first && n > second) {
                    second = n;
                }
            }
        }
        return second;
    }
};