504 Base 7

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].

class Solution {
  public String convertToBase7(int num) {
    return Integer.toString(num, 7);
  }
}