README.md

1796. 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 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.

Solutions (Rust)

1. Solution

impl Solution {
    pub fn second_highest(s: String) -> i32 {
        let mut digits = [false; 10];

        for c in s.bytes() {
            if c.is_ascii_digit() {
                digits[(c - b'0') as usize] = true;
            }
        }

        (0..=9)
            .rev()
            .skip_while(|&x| !digits[x as usize])
            .skip(1)
            .find(|&x| digits[x as usize])
            .unwrap_or(-1)
    }
}