Base 7

Question

Given an integer, return its base 7 string representation.

Example 1:

Input: 100
Output: "202"

Example 2:

Input: -7
Output: "-10"

Note: The input will be in range of [-1e7, 1e7].

Tags

• Mathematics

Thought

Be careful the processes of converting from other base to decimal number and converting from the decimal number to other base are different! Suggest to use string.

Code

class Solution(object):
    def convertToBase7(self, num):
        """
        :type num: int
        :rtype: str
        """
        if num == 0:
            return '0'
        absValue = abs(num)
        sig = num / absValue
        ans = ''
        while absValue:
            ans = str(absValue % 7) + ans
            absValue /= 7
        if sig < 0:
            return '-' + ans
        else:
            return ans