[leetcode: Python]504. Base 7

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].

实现七进制

方法一：68ms

class Solution(object):    def convertToBase7(self, num):        """        :type num: int        :rtype: str        """        s = ''        if num == 0:            return '0'        sig = 0        if num < 0:            num = abs(num)            sig = 1        c = 0        while num:            num, c = divmod(num, 7)            s = str(c) + s        if sig == 1:            return '-' + s        return s

方法二：56ms

class Solution(object):    def convertToBase7(self, num):        """        :type num: int        :rtype: str        """        if not num:            return '0'        ans=[]        sgn='-' if num<0 else ''        num=abs(num)        while num:            ans.append(str(num%7))            num/=7        return sgn+''.join(ans[::-1])

方法三：36ms

class Solution(object):    def convertToBase7(self, num):        if num==0:            return "0"        res=''        n=abs(num)        while n:            res=str(n%7)+res            n//=7        return res if num>0 else '-'+res