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

1796. Second Largest Digit in a String

Level

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.

• Java
• C++
• Python

• 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;
      }
  }
  

• // 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());
      }
  };
  

• # 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
  
  

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