[LeetCode] 504. Base 7_Easy tag: Math

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].

 

不停除以7, 然后把余数放到ans里面, 最后reverse ans加上符号即可.

Code

class Solution:
    def convertToBase7(self, num):
        if num == 0: return '0'
        pos = "-" if num < 0 else ""
        num, ans = abs(num), ''
        while num > 0:
            rem, num = divmod(num, 7)
            ans += str(num)
            num = rem
        return pos + ans[::-1]