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
class Solution {
    public List<String> commonChars(String[] words) {
        int[] cnt = new int[26];
        Arrays.fill(cnt, 20000);
        for (var w : words) {
            int[] t = new int[26];
            for (int i = 0; i < w.length(); ++i) {
                ++t[w.charAt(i) - 'a'];
            }
            for (int i = 0; i < 26; ++i) {
                cnt[i] = Math.min(cnt[i], t[i]);
            }
        }
        List<String> ans = new ArrayList<>();
        for (int i = 0; i < 26; ++i) {
            ans.addAll(Collections.nCopies(cnt[i], String.valueOf((char) ('a' + i))));
        }
        return ans;
    }
}
