<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:
    vector<string> commonChars(vector<string>& words) {

        unordered_map<string, int> alpFreq;
        for(char letter: words[0]){
            alpFreq[string(1,letter)]++;
        }
        vector<string> ans;
        for(string word: words){
            ans.clear();
            for(char c : word){
                if(alpFreq.find(string(1,c)) != alpFreq.end()){
                    alpFreq[string(1,c)]--;
                    if(alpFreq[string(1,c)] >= 0){
                        ans.push_back(string(1,c));
                    }
                }
            }
            alpFreq.clear();
            for(string letter: ans){
                alpFreq[letter]++;
            }
        }
        return ans;
    }
};
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