[leetcode]504. Base 7

题目链接：https://leetcode.com/problems/base-7/#/description

Given an integer, return its base 7 string representation.

Example 1:

Input: 100
Output: "202"

Example 2:

Input: -7
Output: "-10"

class Solution {
public:
string convertToBase7(int num) {
if(num==0)
return "0";

int number=abs(num);
string res="";
while(number)
{
int n=number%7;
res=to_string(n)+res;
number/=7;
}
if(num<0)
res="-"+res;
return res;
}
};