Is Find the K-Beauty of a Number easy or hard?

Find the K-Beauty of a Number is classified as an Easy problem. The logic involves basic string traversal and divisibility checks. The challenge is recognizing the sliding window optimization that avoids repeatedly converting substrings to integers.

Find the K-Beauty of a Number Python/Java solution

Most implementations convert the number to a string and iterate through substrings of length k. Python, Java, C++, and similar languages can check each substring, convert it to an integer, and verify whether it divides the original number. The optimized version updates the value using sliding window arithmetic for O(n) performance.

How to solve Find the K-Beauty of a Number in O(n)?

Convert the number to a string and maintain a sliding window of length k. Track the numeric value of the current window and update it when the window moves by removing the leftmost digit and adding the new digit. At each step, check if the value is non-zero and divides the original number.

What is the best approach for Find the K-Beauty of a Number?

The sliding window approach is the most efficient solution. It maintains the numeric value of the current k-length substring while moving across the digits, avoiding repeated substring-to-integer conversions. This reduces the time complexity to O(n) with O(1) extra space.

Is Find the K-Beauty of a Number asked at Google/Amazon/Meta?

Problems involving digit manipulation, substring extraction, and sliding window logic frequently appear in interviews at large tech companies. While this exact question may vary, the same techniques—string processing and window-based iteration—are common in coding interviews at companies like Amazon and Google.

What data structure is used in Find the K-Beauty of a Number?

The solution mainly uses string processing and simple integer arithmetic. The optimized version relies on the sliding window technique rather than a complex data structure. Only a few variables are required to track the current window value and the count of valid substrings.

What is the time complexity of Find the K-Beauty of a Number?

The optimal sliding window solution runs in O(n) time where n is the number of digits in the number. A simpler approach that extracts each substring and converts it to an integer takes O(n * k) time because each substring conversion costs O(k). Both approaches use O(1) extra space.

Description Hints 2 Solution Video 3:47

2269. Find the K-Beauty of a Number

Easy63.8% acceptance3 companies

The k-beauty of an integer num is defined as the number of substrings of num when it is read as a string that meet the following conditions:

It has a length of k.
It is a divisor of num.

Given integers num and k, return the k-beauty of num.

Note:

Leading zeros are allowed.
0 is not a divisor of any value.

A substring is a contiguous sequence of characters in a string.

Example 1:

Input: num = 240, k = 2
Output: 2
Explanation: The following are the substrings of num of length k:
- "24" from "240": 24 is a divisor of 240.
- "40" from "240": 40 is a divisor of 240.
Therefore, the k-beauty is 2.

Example 2:

Input: num = 430043, k = 2
Output: 2
Explanation: The following are the substrings of num of length k:
- "43" from "430043": 43 is a divisor of 430043.
- "30" from "430043": 30 is not a divisor of 430043.
- "00" from "430043": 0 is not a divisor of 430043.
- "04" from "430043": 4 is not a divisor of 430043.
- "43" from "430043": 43 is a divisor of 430043.
Therefore, the k-beauty is 2.

Constraints:

1 <= num <= 10⁹
1 <= k <= num.length (taking num as a string)

Asked at 3 companies

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Topics

Hints open one at a time

Hint 1

We should check all the substrings of num with a length of k and see if it is a divisor of num.

Hint 2

We can more easily obtain the substrings by converting num into a string and converting back to an integer to check for divisibility.

3:47

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

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1class Solution:
2    def divisorSubstrings(self, num: int, k: int) -> int:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

240
2

Input

430043
2

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