Given an integer `n`, return a binary string representing its representation in base `-2`.

Note that the returned string should not have leading zeros unless the string is `"0"`.

Example 1:

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

Example 2:

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

Example 3:

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

Constraints:

- `0 <= n <= 109`