Convert an integer
num to base 7.Example 1
Input: num = 100
Output: "202"
Explanation: 100 in base 7 is 202.
Output: "202"
Explanation: 100 in base 7 is 202.
Example 2
Input: num = -7
Output: "-10"
Explanation: -7 in base 7 is -10.
Output: "-10"
Explanation: -7 in base 7 is -10.