LeetCode-504. Base 7 [C++][Java]

LeetCode-504. base 7https://leetcode.com/problems/base-7/

Given an integer num, return a string of its base 7 representation.

Example 1:

Input: num = 100
Output: "202"

Example 2:

Input: num = -7
Output: "-10"

Constraints:

-10^7 <= num <= 10^7

class Solution {
public:
    string convertTobase7(int num) {
        if (num == 0) {return "0";}
        bool is_negative = num < 0;
        if (is_negative) {num = -num;}
        string ans;
        while (num > 0) {
            int a = num / 7, b = num % 7;
            ans = to_string(b) + ans;
            num = a;
        }
        return is_negative ? "-" + ans : ans;
    }
};

class Solution {
    public String convertTobase7(int num) {
        if (num == 0) {return "0";}
        boolean is_negative = num < 0;
        if (is_negative) {num = -num;}
        String ans = "";
        while (num > 0) {
            int a = num / 7, b = num % 7;
            ans = Integer.toString(b) + ans;
            num = a;
        }
        return is_negative ? "-" + ans : ans;
    }
}