LeetCode 1796. Second Largest Digit in a String

Description

https://leetcode.com/problems/second-largest-digit-in-a-string/

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

An alphanumericstring 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.

Explanation

Create a set to store numerical digits and find out the second-largest number.

Python Solution

class Solution:
    def secondHighest(self, s: str) -> int:
        digit_set = set()
        for c in s:
            if c.isdigit():
                digit_set.add(int(c))
        
        if len(digit_set) < 2:
            return -1
        
        return sorted(list(digit_set))[-2]