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# 0916. Word Subsets

<https://leetcode.com/problems/word-subsets>

## Description

You are given two string arrays `words1` and `words2`.

A string `b` is a **subset** of string `a` if every letter in `b` occurs in `a` including multiplicity.

* For example, `"wrr"` is a subset of `"warrior"` but is not a subset of `"world"`.

A string `a` from `words1` is **universal** if for every string `b` in `words2`, `b` is a subset of `a`.

Return an array of all the **universal** strings in `words1`. You may return the answer in **any order**.

**Example 1:**

```
**Input:** words1 = ["amazon","apple","facebook","google","leetcode"], words2 = ["e","o"]
**Output:** ["facebook","google","leetcode"]
```

**Example 2:**

```
**Input:** words1 = ["amazon","apple","facebook","google","leetcode"], words2 = ["l","e"]
**Output:** ["apple","google","leetcode"]
```

**Example 3:**

```
**Input:** words1 = ["amazon","apple","facebook","google","leetcode"], words2 = ["e","oo"]
**Output:** ["facebook","google"]
```

**Example 4:**

```
**Input:** words1 = ["amazon","apple","facebook","google","leetcode"], words2 = ["lo","eo"]
**Output:** ["google","leetcode"]
```

**Example 5:**

```
**Input:** words1 = ["amazon","apple","facebook","google","leetcode"], words2 = ["ec","oc","ceo"]
**Output:** ["facebook","leetcode"]
```

**Constraints:**

* `1 <= words1.length, words2.length <= 104`
* `1 <= words1[i].length, words2[i].length <= 10`
* `words1[i]` and `words2[i]` consist only of lowercase English letters.
* All the strings of `words1` are **unique**.

## ac

```java
```