<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>

class Solution {
public:
    // time/space: O(nk)/O(1)
    vector<string> commonChars(vector<string>& words) {
       
        vector<int> minCount(26, INT_MAX);
        for (auto& word : words) {
          
            vector<int> count(26, 0);
            for (auto& c : word) count[c - 'a']++;
            for (int c = 0; c < 26; c++) minCount[c] = min(minCount[c], count[c]);
        }

        vector<string> result;
        for (int c = 0; c < 26; c++) {
            for (int i = 0; i < minCount[c]; i++) result.push_back(string(1, 'a' + c));
        }
        return result;
    }
};
12000