Smallest Value of the Rearranged Number
<p>You are given an integer <code>num.</code> <strong>Rearrange</strong> the digits of <code>num</code> such that its value is <strong>minimized</strong> and it does not contain <strong>any</strong> leading zeros.</p>

<p>Return <em>the rearranged number with minimal value</em>.</p>

<p>Note that the sign of the number does not change after rearranging the digits.</p>

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

<pre>
<strong>Input:</strong> num = 310
<strong>Output:</strong> 103
<strong>Explanation:</strong> The possible arrangements for the digits of 310 are 013, 031, 103, 130, 301, 310. 
The arrangement with the smallest value that does not contain any leading zeros is 103.
</pre>

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

<pre>
<strong>Input:</strong> num = -7605
<strong>Output:</strong> -7650
<strong>Explanation:</strong> Some possible arrangements for the digits of -7605 are -7650, -6705, -5076, -0567.
The arrangement with the smallest value that does not contain any leading zeros is -7650.
</pre>

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

<ul>
	<li><code>-10<sup>15</sup> &lt;= num &lt;= 10<sup>15</sup></code></li>
</ul>
Math; Sorting
func smallestNumber(num int64) (ans int64) {
	neg := num < 0
	num = max(num, -num)
	cnt := make([]int, 10)

	for num > 0 {
		cnt[num%10]++
		num /= 10
	}

	if neg {
		for i := 9; i >= 0; i-- {
			for cnt[i] > 0 {
				ans = ans*10 + int64(i)
				cnt[i]--
			}
		}
		return -ans
	}

	if cnt[0] > 0 {
		for i := 1; i < 10; i++ {
			if cnt[i] > 0 {
				cnt[i]--
				ans = int64(i)
				break
			}
		}
	}

	for i := 0; i < 10; i++ {
		for cnt[i] > 0 {
			ans = ans*10 + int64(i)
			cnt[i]--
		}
	}

	return ans
}
