Find Common Characters
<p>Given a string array <code>words</code>, return <em>an array of all characters that show up in all strings within the </em><code>words</code><em> (including duplicates)</em>. You may return the answer in <strong>any order</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> words = ["bella","label","roller"]
<strong>Output:</strong> ["e","l","l"]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> words = ["cool","lock","cook"]
<strong>Output:</strong> ["c","o"]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= words.length &lt;= 100</code></li>
	<li><code>1 &lt;= words[i].length &lt;= 100</code></li>
	<li><code>words[i]</code> consists of lowercase English letters.</li>
</ul>
Array; Hash Table; String
func commonChars(words []string) (ans []string) {
	cnt := make([]int, 26)
	for i := range cnt {
		cnt[i] = 20000
	}
	for _, w := range words {
		t := make([]int, 26)
		for _, c := range w {
			t[c-'a']++
		}
		for i := 0; i < 26; i++ {
			cnt[i] = min(cnt[i], t[i])
		}
	}
	for i := 0; i < 26; i++ {
		for j := 0; j < cnt[i]; j++ {
			ans = append(ans, string('a'+rune(i)))
		}
	}
	return ans
}
