class Solution:

"""

@param num: the given number

@return: The base 7 string representation

"""

def convertToBase7(self, num):

# Write your code here

minus = False

if num < 0:

num = -num;

minus = True

digits = []

while num >= 7:

digits.append(num % 7)

num = int(num / 7)

digits.append(num)

k = 1

ret = 0

for d in digits:

ret += d * k

k *= 10

if minus:

return str(-ret)

return str(ret)

# easy: https://www.lintcode.com/problem/base-7/