Is Find the Key of the Numbers easy or hard?

Find the Key of the Numbers is categorized as an Easy problem. It mainly tests understanding of digit positions, simple comparisons, and number manipulation. Most solutions are implemented in a few lines using either string processing or basic math.

Find the Key of the Numbers Python/Java solution

In Python or Java, convert numbers to 4-digit strings and compare digits position by position, or repeatedly extract digits using % 10 and / 10. The minimum digit from the three numbers at each place forms the final key. Both implementations run in constant time due to the fixed number of digits.

How to solve Find the Key of the Numbers in O(n)?

Treat each number as a 4-digit value and process one digit position at a time. Extract digits either by string indexing or by using modulo and division operations. Compute the minimum digit among the three numbers at each position and append it to the result key. The algorithm runs in O(d) time with constant space when using arithmetic operations.

What is the best approach for Find the Key of the Numbers?

The mathematical digit extraction approach is typically considered the best. It processes each digit using modulo (% 10) and division (/ 10) operations and builds the result numerically. The algorithm runs in O(d) time where d is the number of digits (4 here) and uses O(1) extra space.

Is Find the Key of the Numbers asked at Google/Amazon/Meta?

This problem belongs to the easy math category and is mainly used for practice on digit manipulation and basic algorithmic thinking. Similar digit-processing problems appear in interviews at companies like Amazon and Google, especially in early screening rounds.

What data structure is used in Find the Key of the Numbers?

No complex data structures are required. The solution mainly relies on basic arithmetic operations or simple string manipulation. The core concept comes from math-based digit extraction and positional comparison.

What is the time complexity of Find the Key of the Numbers?

Both common solutions run in O(d) time where d is the number of digits in the numbers. Since the problem always works with 4-digit values, the runtime is effectively constant. Space complexity is O(d) for the string method and O(1) for the mathematical approach.

3270. Find the Key of the Numbers - Practice Online

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 i^th digit (1 <= i <= 4) 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 (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 1^st digit of the key is min(0, 0, 1).
The 2^nd digit of the key is min(0, 0, 0).
The 3^rd digit of the key is min(0, 1, 0).
The 4^th 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