Introduction

In this blog post, we will explore how to solve the LeetCode problem "2264" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

You are given a string num representing a large integer. An integer is good if it meets the following conditions: It is a substring of num with length 3. It consists of only one unique digit. Return the maximum good integer as a string or an empty string "" if no such integer exists. Note: A substring is a contiguous sequence of characters within a string. There may be leading zeroes in num or a good integer. Example 1: Input: num = "6777133339" Output: "777" Explanation: There are two distinct good integers: "777" and "333". "777" is the largest, so we return "777". Example 2: Input: num = "2300019" Output: "000" Explanation: "000" is the only good integer. Example 3: Input: num = "42352338" Output: "" Explanation: No substring of length 3 consists of only one unique digit. Therefore, there are no good integers. Constraints: 3 <= num.length <= 1000 num only consists of digits.

Explanation

Here's the breakdown of the solution:

• Iterate through substrings of length 3: Check each substring of length 3 within the input string.
• Check for uniqueness: For each substring, verify if all characters are the same.

• Track the maximum: If a substring consists of the same digit, compare it with the current maximum good integer found so far, and update if necessary.

• Time Complexity: O(n), where n is the length of the input string.

• Space Complexity: O(1)

Code

    def largestGoodInteger(num: str) -> str:
    """
    Finds the largest "good" integer (substring of length 3 with same digits) within a given string.

    Args:
        num: The input string representing a large integer.

    Returns:
        The largest good integer as a string, or an empty string if none exists.
    """
    max_good_integer = ""
    for i in range(len(num) - 2):
        substring = num[i:i + 3]
        if substring[0] == substring[1] == substring[2]:
            if max_good_integer == "" or substring > max_good_integer:
                max_good_integer = substring
    return max_good_integer