Convert to Base -2
<p>Given an integer <code>n</code>, return <em>a binary string representing its representation in base</em> <code>-2</code>.</p>

<p><strong>Note</strong> that the returned string should not have leading zeros unless the string is <code>&quot;0&quot;</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> n = 2
<strong>Output:</strong> &quot;110&quot;
<strong>Explantion:</strong> (-2)<sup>2</sup> + (-2)<sup>1</sup> = 2
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> n = 3
<strong>Output:</strong> &quot;111&quot;
<strong>Explantion:</strong> (-2)<sup>2</sup> + (-2)<sup>1</sup> + (-2)<sup>0</sup> = 3
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> n = 4
<strong>Output:</strong> &quot;100&quot;
<strong>Explantion:</strong> (-2)<sup>2</sup> = 4
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>0 &lt;= n &lt;= 10<sup>9</sup></code></li>
</ul>
Math
function baseNeg2(n: number): string {
    if (n === 0) {
        return '0';
    }
    let k = 1;
    const ans: string[] = [];
    while (n) {
        if (n % 2) {
            ans.push('1');
            n -= k;
        } else {
            ans.push('0');
        }
        k *= -1;
        n /= 2;
    }
    return ans.reverse().join('');
}
