Second Largest Digit in a String.cpp

// Runtime: 9 ms (Top 31.49%) | Memory: 6.6 MB (Top 98.16%)
class Solution {
public:
    int secondHighest(string s) {
        // support variables
        int res[2] = {-1, -1};
        // parsing s
        for (char c: s) {
            // considering only numerical characters
            if (c >= '0' && c <= '9') {
                // normalising c
                c -= '0';
                // updating res
                if (c > res[0]) {
                    res[1] = res[0];
                    res[0] = c;
                } else if (c != res[0] && c > res[1]) res[1] = c;
            }
        }
        return res[1];
    }
};