1017. Convert to Base -2

Given a number N, return a string consisting of "0"s and "1"s that represents its value in base -2 (negative two).

The returned string must have no leading zeroes, unless the string is "0".

 

Example 1:

Input: 2
Output: "110" Explantion: (-2) ^ 2 + (-2) ^ 1 = 2 

Example 2:

Input: 3
Output: "111" Explantion: (-2) ^ 2 + (-2) ^ 1 + (-2) ^ 0 = 3 

Example 3:

Input: 4
Output: "100" Explantion: (-2) ^ 2 = 4

 

Note:

1. 0 <= N <= 10^9

 

Approach #1: Math. [Java]

class Solution {
    public String baseNeg2(int N) {
        if (N == 0) return "0";
        StringBuilder sb = new StringBuilder();
        while (N != 0) {
            int remainder = N % (-2);
            N /= -2;
            if (remainder < 0) {
                remainder += 2;
                N += 1;
            }
            sb.append(remainder);
        }
        return sb.reverse().toString();
    }
}

　　

Reference:

https://en.wikipedia.org/wiki/Negative_base#Calculation

https://www.geeksforgeeks.org/convert-number-negative-base-representation/