<p>You are given two string arrays <code>words1</code> and <code>words2</code>.</p>

<p>A string <code>b</code> is a <strong>subset</strong> of string <code>a</code> if every letter in <code>b</code> occurs in <code>a</code> including multiplicity.</p>

<ul>
	<li>For example, <code>&quot;wrr&quot;</code> is a subset of <code>&quot;warrior&quot;</code> but is not a subset of <code>&quot;world&quot;</code>.</li>
</ul>

<p>A string <code>a</code> from <code>words1</code> is <strong>universal</strong> if for every string <code>b</code> in <code>words2</code>, <code>b</code> is a subset of <code>a</code>.</p>

<p>Return an array of all the <strong>universal</strong> strings in <code>words1</code>. 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> words1 = [&quot;amazon&quot;,&quot;apple&quot;,&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;], words2 = [&quot;e&quot;,&quot;o&quot;]
<strong>Output:</strong> [&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> words1 = [&quot;amazon&quot;,&quot;apple&quot;,&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;], words2 = [&quot;l&quot;,&quot;e&quot;]
<strong>Output:</strong> [&quot;apple&quot;,&quot;google&quot;,&quot;leetcode&quot;]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= words1.length, words2.length &lt;= 10<sup>4</sup></code></li>
	<li><code>1 &lt;= words1[i].length, words2[i].length &lt;= 10</code></li>
	<li><code>words1[i]</code> and <code>words2[i]</code> consist only of lowercase English letters.</li>
	<li>All the strings of <code>words1</code> are <strong>unique</strong>.</li>
</ul>


#include <string>
#include <vector>
#include <algorithm>



class Solution {
public:
    std::vector<std::string> wordSubsets(std::vector<std::string>& words1, std::vector<std::string>& words2) {
		std::vector<std::string> result;
		std::vector<int> char_count('z' + 1, 0);
		std::vector<int> total_char_count('z' + 1, 0);

		for (auto& word2 : words2) {
			for (char c : word2)
				++char_count[c];

			for (int i = 'a'; i <= 'z'; ++i) {
				total_char_count[i] = std::max(total_char_count[i], char_count[i]);
				char_count[i] = 0;
			}
		}

		for (auto& word1 : words1) {
			bool is_universal = true;

			for (char c : word1)
				++char_count[c];

			for (int i = 'a'; i <= 'z'; ++i) {
				if (is_universal && char_count[i] < total_char_count[i])
					is_universal = false;

				char_count[i] = 0;
			}

			if (is_universal)
				result.emplace_back(word1);
		}

		return result;
    }
};
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