1017. Convert to Base -2 

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class Solution {
    public String baseNeg2(int n) {
        if (n == 0) {
            return "0";
        }

        StringBuilder sb = new StringBuilder();
        while (n != 0) {
            int x = n % (-2);
            n /= (-2);
            if (x == -1) {
                // 注意 Java 取余结果的符号与第一个操作数的符号相同，(-1) % (-2) = (-1)
                // 调整前：-1 = (-2) * 0 + (-1)
                // 调整后：-1 = (-2) * 1 + 1
                x = 1; // 此处将余数从 -1 调整为 1 等于减去了 -2，所以下面的商要增加 1 个 -2
                n++;
            }
            sb.append(x);
        }

        return sb.reverse().toString();
    }
}

References

1017. Convert to Base -2
Java: Remainder (modulo) operator with negative numbers