1796. Second Largest Digit in a String

#### QUESTION:

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:

``````class Solution {
func secondHighest(_ s: String) -> Int {
var set:Set<Int> = Set()
for ch in s {
if ch.asciiValue! >= Character("0").asciiValue!
&& ch.asciiValue! <= Character("9").asciiValue! {
set.insert(Int(String(ch))!)
}
}
let arr = set.sorted()
if arr.count >= 2 {
return arr[arr.count - 2]
}
return -1
}
}
``````