Write an Integer Using Base Seven Digits
Company: Google
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Other
### Problem
Return the base-seven string for num, using digits 0 through 6 and a leading minus sign only for negative values. Zero is represented by "0".
```cpp
class Solution {
public:
string convertToBase7(int num);
};
```
### Examples
**Example 1:**
```text
num = 50
Output: "101"
Explanation: 50 = 1*49 + 0*7 + 1.
```
**Example 2:**
```text
num = -15
Output: "-21"
Explanation: 15 = 2*7 + 1.
```
### Constraints
- Input num ranges from -10000000 through 10000000, inclusive.
### Clarifying Questions
Preserve the sign and ensure every output digit is in the base-seven alphabet.
```hint Read the boundary condition
What does the remainder of division by seven tell you about the last digit?
```
### Contract considerations
Preserve the sign and ensure every output digit is in the base-seven alphabet.
Overview: Write an Integer Using Base Seven Digits. Return the base-seven string for num, using digits 0 through 6 and a leading minus sign only for negative values.