# [LeetCode]#504. Base 7

Environment: Python 3.7

Key technique: divmod function

Given an integer, return its base 7 string representation.

Example 1:

`Input: 100Output: "202"`

Example 2:

`Input: -7Output: "-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

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