Find the Key of the Numbers

Problem Description

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:

1. If any number has less than four digits, it is padded with leading zeros.
2. The i-th digit of the key is generated by taking the smallest digit among the i-th digits of num1, num2, and num3.

Return the key of the three numbers without leading zeros.

Key Insights

• Each number can be represented as a four-digit string by padding with leading zeros.
• We can iterate through the digits of these strings to find the minimum digit at each position.
• The final key is formed by concatenating these minimum digits.
• Leading zeros in the final output should be removed.

Space and Time Complexity

Time Complexity: O(1) since the maximum number of digits we are dealing with is fixed (4). Space Complexity: O(1) as we are using a constant amount of space for processing.

Solution

To solve this problem, we will:

1. Convert each integer to a four-digit string using leading zeros.
2. Extract the digits of each string and compare them position by position.
3. Store the minimum digit for each position and construct the final key.
4. Convert the key string to an integer to remove any leading zeros before returning it.

Code Solutions