Find The Least Frequent Digit
<p>Given an integer <code>n</code>, find the digit that occurs <strong>least</strong> frequently in its decimal representation. If multiple digits have the same frequency, choose the <strong>smallest</strong> digit.</p>

<p>Return the chosen digit as an integer.</p>
The <strong>frequency</strong> of a digit <code>x</code> is the number of times it appears in the decimal representation of <code>n</code>.
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">n = 1553322</span></p>

<p><strong>Output:</strong> 1</p>

<p><strong>Explanation:</strong></p>

<p>The least frequent digit in <code>n</code> is 1, which appears only once. All other digits appear twice.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">n = 723344511</span></p>

<p><strong>Output:</strong> 2</p>

<p><strong>Explanation:</strong></p>

<p>The least frequent digits in <code>n</code> are 7, 2, and 5; each appears only once.</p>
</div>

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

<ul>
	<li><code>1 &lt;= n &lt;= 2<sup>31</sup>​​​​​​​ - 1</code></li>
</ul>
func getLeastFrequentDigit(n int) (ans int) {
	cnt := [10]int{}
	for ; n > 0; n /= 10 {
		cnt[n%10]++
	}
	f := 1 << 30
	for x, v := range cnt {
		if v > 0 && v < f {
			f = v
			ans = x
		}
	}
	return
}
