【LeetCode】504. Base 7【E】【94】

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].

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就是进制转换

最开始就写了简单的迭代版本 后来看答案有递归版本 对呀，这个题目适合用递归来做呀

class Solution(object):
    def convertToBase7(self, num):
        
        if num < 0:
            return '-' + self.convertToBase7(-num)
        if num < 7:
            return str(num)
        return self.convertToBase7(num / 7) + str(num % 7)
        
        '''
        res = ''
        minus = ''
        
        if num < 0:
            minus = '-'
            num = -num
        
        while (num) >= 0:
            res += str(num % 7)
            num = num / 7
            if num == 0:
                break
        
        return minus + res[::-1]
        '''