[LeetCode]#504. Base 7

Environment: Python 3.7

Key technique: divmod function

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].

Analysis:

Use divmod function to find quotient and remainder dividing by 7. The 10 Base convert to 7 Base number is as below.

Therefore, the process example is as below.

We also need consider negative case.

Solution:

class Solution(object):
    def convertToBase7(self, num):
        ans = ''
        if num == 0:
            return '0'
        neg = False
        if num < 0:
            num = abs(num)
            neg = True
        c = 0
        while num:
            num, c = divmod(num, 7)
            ans = str(c) + ans
        if neg is True:
            return '-' + ans
        return ans

Reference:

https://blog.csdn.net/NXHYD/article/details/72478883