LeetCode 504. Base 7

Description

https://leetcode.com/problems/base-7/

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

Explanation

Keep dividing num until n < 7, add all remainders. Then finally add the last quotient. If num is negative, add “-” before the result.

Python Solution

class Solution:
    def convertToBase7(self, num: int) -> str:
        is_negative = False
        if num < 0:
            num = -num
            is_negative = True
        
        result = ""
        while num >= 7:
            result += str(num % 7)
            num = num // 7
            
        result += str(num)
        
        if is_negative:
            return "-" + result[::-1]
        
        return result[::-1]
  • Time Complexity: O(N).
  • Space Complexity: O(N).

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