Introduction

In this blog post, we will explore how to solve the LeetCode problem "3270" 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 three positive integers num1, num2, and num3. The key of num1, num2, and num3 is defined as a four-digit number such that: Initially, if any number has less than four digits, it is padded with leading zeros. The ith digit (1 <= i <= 4) of the key is generated by taking the smallest digit among the ith digits of num1, num2, and num3. Return the key of the three numbers without leading zeros (if any). Example 1: Input: num1 = 1, num2 = 10, num3 = 1000 Output: 0 Explanation: On padding, num1 becomes "0001", num2 becomes "0010", and num3 remains "1000". The 1st digit of the key is min(0, 0, 1). The 2nd digit of the key is min(0, 0, 0). The 3rd digit of the key is min(0, 1, 0). The 4th digit of the key is min(1, 0, 0). Hence, the key is "0000", i.e. 0. Example 2: Input: num1 = 987, num2 = 879, num3 = 798 Output: 777 Example 3: Input: num1 = 1, num2 = 2, num3 = 3 Output: 1 Constraints: 1 <= num1, num2, num3 <= 9999

Explanation

• Padding: Pad the numbers with leading zeros to ensure each number has exactly four digits.
  • Digit-wise Minimum: Iterate through the digits (from left to right), finding the minimum digit among the corresponding digits of the three padded numbers.
  • Key Generation: Concatenate the minimum digits to form the key, and remove leading zeros.

• Runtime Complexity: O(1) (Since the numbers are bounded by 9999, the number of operations is constant). Storage Complexity: O(1).

Code

    def find_key(num1: int, num2: int, num3: int) -> int:
    """
    Given three positive integers num1, num2, and num3. The key of num1, num2, and num3 is defined as a four-digit number such that:
    Initially, if any number has less than four digits, it is padded with leading zeros.
    The ith digit (1 <= i <= 4) of the key is generated by taking the smallest digit among the ith digits of num1, num2, and num3.
    Return the key of the three numbers without leading zeros (if any).

    For example:
    find_key(1, 10, 1000) == 0
    find_key(987, 879, 798) == 777
    find_key(1, 2, 3) == 1
    """
    s1 = str(num1).zfill(4)
    s2 = str(num2).zfill(4)
    s3 = str(num3).zfill(4)

    key = ""
    for i in range(4):
        key += min(s1[i], s2[i], s3[i])

    key = key.lstrip('0')
    if not key:
        return 0
    return int(key)