Base 7 Python Solution with Tests

Tested Python solution for LeetCode 504 with 25 pytest cases. Generate a practice environment with lcpy.

LeetCode 504, Easy. Topics: Math, String. View on LeetCode.

Generate this problem as a practice environment: tested reference solution, 25 parametrized pytest cases, and a playground notebook:

lcpy gen -n 504   # by problem number
lcpy gen -s base_7   # by problem name

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Problem

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

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Examples

Input: num = 100
Output: "202"

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

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Constraints

• -10^7 <= num <= 10^7

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Solution

Reference implementation from solution.py on GitHub, full suite in test_solution.py:

class Solution:
    # Time: O(log_7 |num|)
    # Space: O(log_7 |num|)
    def convert_to_base_7(self, num: int) -> str:
        if num == 0:
            return "0"
        negative = num < 0
        digits = ""
        value = abs(num)
        while value:
            digits = str(value % 7) + digits
            value //= 7
        return f"-{digits}" if negative else digits

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Complexity

Time	Space
O(log_7	num	)	O(log_7	num	)

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