Is Base 7 easy or hard?

Base 7 is categorized as an easy problem. The core idea is simple base conversion using division and remainder. Candidates mainly need to handle negative numbers and build the digits in the correct order.

How to solve Base 7 in O(n)?

The problem is typically solved in O(log₇ n) time rather than O(n). Each division by 7 reduces the number significantly, and the number of iterations equals the number of digits in base 7. Implement a loop that repeatedly computes remainder (num % 7) and integer division (num // 7) until the value reaches zero.

What is the best approach for Base 7?

The iterative division approach is the most practical solution. Repeatedly divide the number by 7, record the remainder as the next digit, and continue until the number becomes zero. Reverse the collected digits to form the final base‑7 string. This method runs in O(log₇ n) time and uses O(log₇ n) space for the result.

What data structure is used in Base 7?

No complex data structure is required. The solution mainly uses arithmetic operations and a string or character buffer to store digits as they are generated. The algorithm belongs to the math category and sometimes uses recursion if implemented recursively.

What is the time complexity of Base 7?

The time complexity is O(log₇ n). Each step divides the number by 7, so the total number of operations equals the number of base‑7 digits in the number. Space complexity is also O(log₇ n) because the output string contains that many digits.

Base 7 Python or Java solution approach?

Both Python and Java implementations follow the same logic: repeatedly divide the number by 7 and append the remainder to a result string or builder. Python often uses string concatenation or a list that is reversed, while Java typically uses a StringBuilder for efficient digit construction.

Is Base 7 asked at Google, Amazon, or Meta?

Base conversion problems like Base 7 occasionally appear in interviews at large tech companies because they test basic number manipulation and reasoning about arithmetic operations. While not among the most frequent questions, it represents the type of simple math and implementation problem candidates should handle quickly.

Description Solution Video 5:20

504. Base 7

Easy55.3% acceptance4 companies

Given an integer num, return a string of its base 7 representation.

Example 1:

Input: num = 100
Output: "202"

Example 2:

Input: num = -7
Output: "-10"

Constraints:

-10⁷ <= num <= 10⁷

Asked at 4 companies

Microsoft Amazon

Google Bloomberg

Topics

Math

5:20

Still stuck?Read 3 approaches, or watch a walkthrough.

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1class Solution:
2    def convertToBase7(self, num: int) -> str:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

-7

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