Is Second Largest Digit in a String easy or hard?

The problem is categorized as Easy on LeetCode with an acceptance rate around 54%. The main challenge is ensuring digits are distinct while correctly updating the two largest values during a single pass.

Second Largest Digit in a String Python/Java solution

Python and Java implementations usually follow the same pattern: iterate through the string, check if each character is a digit, convert it to an integer, and update the largest and second largest variables. The logic stays identical across languages with O(n) time and O(1) space.

How to solve Second Largest Digit in a String in O(n)?

Iterate through the string and process only numeric characters. Maintain two variables: the largest digit and the second largest distinct digit. Update them whenever a larger value appears or when a value falls between the current two. This single-pass approach guarantees O(n) time and constant space.

What is the best approach for Second Largest Digit in a String?

The most efficient approach is scanning the string once while tracking the two largest distinct digits using two variables. This avoids extra data structures and sorting. The algorithm runs in O(n) time and O(1) space because only two values are stored while iterating through the string.

Is Second Largest Digit in a String asked at Google/Amazon/Meta?

Problems involving scanning strings and tracking top elements appear frequently in interviews at companies like Amazon, Google, and Meta. While this exact problem may not always appear, the pattern of maintaining the top two values in one pass is a common interview technique.

What data structure is used in Second Largest Digit in a String?

Two common choices appear in solutions. A set can store unique digits before sorting them to find the second largest. The optimal solution avoids extra structures and instead uses two integer variables to track the largest and second largest digits during iteration.

What is the time complexity of Second Largest Digit in a String?

The optimal solution runs in O(n) time where n is the length of the string. Each character is inspected once to check whether it is a digit and potentially update the top two values. Space complexity is O(1) because only two variables are used to track the largest and second largest digits.

Description Hints 2 Solution Video 7:37

1796. Second Largest Digit in a String

Easy55.2% acceptance4 companies

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 digits.

Asked at 4 companies

Softwire Meta

Google Microsoft

Topics

Hash Table String

Hints open one at a time

Hint 1

First of all, get the distinct characters since we are only interested in those

Hint 2

Let's note that there might not be any digits.

7:37

Still stuck?Read 4 approaches, or watch a walkthrough.

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