<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) {

        int n = words.size();

        vector<int> hashMap(26,0);

        // Initialize hashMap with the frequency of characters in the first word
        for(int i = 0; i < words[0].size(); i++){
            hashMap[words[0][i] - 'a']++;
        }

        // Compare character frequencies with each subsequent word
        for(int i = 1; i < n; i++){

            vector<int> hashMap2(26,0);

            // Fill hashMap2 with the frequencies of the current word
            for(int j = 0; j < words[i].size(); j++){
                hashMap2[words[i][j] - 'a']++;
            }

            // Update hashMap to store the minimum frequency of each character
            for(int j = 0; j < 26; j++){
                // Manually calculate the minimum without using min() function
                if (hashMap[j] > hashMap2[j]) {
                    hashMap[j] = hashMap2[j];
                }
            }
        }

        // Prepare the result
        vector<string> result;

        for(int i = 0; i < 26; i++){
            while(hashMap[i] > 0){
                // Convert integer back to character manually
                char ch = 'a' + i;
                result.push_back(string(1, ch));  // Using basic string creation
                hashMap[i]--;
            }
        }

        return result;
    }
};

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