Word Subsets
<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>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">words1 = [&quot;amazon&quot;,&quot;apple&quot;,&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;], words2 = [&quot;e&quot;,&quot;o&quot;]</span></p>

<p><strong>Output:</strong> <span class="example-io">[&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;]</span></p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">words1 = [&quot;amazon&quot;,&quot;apple&quot;,&quot;facebook&quot;,&quot;google&quot;,&quot;leetcode&quot;], words2 = [&quot;lc&quot;,&quot;eo&quot;]</span></p>

<p><strong>Output:</strong> <span class="example-io">[&quot;leetcode&quot;]</span></p>
</div>

<p><strong class="example">Example 3:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">words1 = [&quot;acaac&quot;,&quot;cccbb&quot;,&quot;aacbb&quot;,&quot;caacc&quot;,&quot;bcbbb&quot;], words2 = [&quot;c&quot;,&quot;cc&quot;,&quot;b&quot;]</span></p>

<p><strong>Output:</strong> <span class="example-io">[&quot;cccbb&quot;]</span></p>
</div>

<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>
Array; Hash Table; String
class Solution {
public:
    vector<string> wordSubsets(vector<string>& words1, vector<string>& words2) {
        int cnt[26] = {0};
        int t[26];
        for (auto& b : words2) {
            memset(t, 0, sizeof t);
            for (auto& c : b) {
                t[c - 'a']++;
            }
            for (int i = 0; i < 26; ++i) {
                cnt[i] = max(cnt[i], t[i]);
            }
        }
        vector<string> ans;
        for (auto& a : words1) {
            memset(t, 0, sizeof t);
            for (auto& c : a) {
                t[c - 'a']++;
            }
            bool ok = true;
            for (int i = 0; i < 26; ++i) {
                if (cnt[i] > t[i]) {
                    ok = false;
                    break;
                }
            }
            if (ok) {
                ans.emplace_back(a);
            }
        }
        return ans;
    }
};