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Formatted question description: https://leetcode.ca/all/1796.html

# 1796. Second Largest Digit in a String

Easy

## Description

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

Loop over s and count the occurrences of all digits. Then loop over all digits backwards and find the second largest digit that has occurrence greater than 0. If such a digit exists, return the digit. Otherwise, return -1.

• class Solution {
public int secondHighest(String s) {
int[] counts = new int[10];
int length = s.length();
for (int i = 0; i < length; i++) {
char c = s.charAt(i);
if (c >= '0' && c <= '9')
counts[c - '0']++;
}
boolean flag = false;
for (int i = 9; i >= 0; i--) {
if (counts[i] > 0) {
if (!flag)
flag = true;
else
return i;
}
}
return -1;
}
}

############

class Solution {
public int secondHighest(String s) {
int a = -1, b = -1;
for (int i = 0; i < s.length(); ++i) {
char c = s.charAt(i);
if (Character.isDigit(c)) {
int v = c - '0';
if (v > a) {
b = a;
a = v;
} else if (v > b && v < a) {
b = v;
}
}
}
return b;
}
}

• // OJ: https://leetcode.com/problems/second-largest-digit-in-a-string
// Time: O(N)
// Space: O(1)
class Solution {
public:
int secondHighest(string s) {
set<int> st;
for (char c : s) {
if (isdigit(c)) st.insert(c - '0');
}
if (st.size() < 2) return -1;
return *next(st.rbegin());
}
};

• class Solution:
def secondHighest(self, s: str) -> int:
a = b = -1
for c in s:
if c.isdigit():
v = int(c)
if v > a:
a, b = v, a
elif b < v < a:
b = v
return b

############

# 1796. Second Largest Digit in a String
# https://leetcode.com/problems/second-largest-digit-in-a-string

class Solution:
def secondHighest(self, s: str) -> int:
res = set(list(c for c in s if c.isdigit()))

return sorted(list(res))[-2] if len(res) > 1 else -1


• func secondHighest(s string) int {
a, b := -1, -1
for _, c := range s {
if c >= '0' && c <= '9' {
v := int(c - '0')
if v > a {
b, a = a, v
} else if v > b && v < a {
b = v
}
}
}
return b
}

• function secondHighest(s: string): number {
let first = -1;
let second = -1;
for (const c of s) {
if (c >= '0' && c <= '9') {
const num = c.charCodeAt(0) - '0'.charCodeAt(0);
if (first < num) {
[first, second] = [num, first];
} else if (first !== num && second < num) {
second = num;
}
}
}
return second;
}


• impl Solution {
pub fn second_highest(s: String) -> i32 {
let mut first = -1;
let mut second = -1;
for c in s.as_bytes() {
if char::is_digit(*c as char, 10) {
let num = (c - b'0') as i32;
if first < num {
second = first;
first = num;
} else if num < first && second < num {
second = num;
}
}
}
second
}
}