# 0692. Top K Frequent Words

<https://leetcode.com/problems/top-k-frequent-words>

## Description

Given an array of strings `words` and an integer `k`, return *the* `k` *most frequent strings*.

Return the answer **sorted** by **the frequency** from highest to lowest. Sort the words with the same frequency by their **lexicographical order**.

**Example 1:**

```
**Input:** words = ["i","love","leetcode","i","love","coding"], k = 2
**Output:** ["i","love"]
**Explanation:** "i" and "love" are the two most frequent words.
Note that "i" comes before "love" due to a lower alphabetical order.
```

**Example 2:**

```
**Input:** words = ["the","day","is","sunny","the","the","the","sunny","is","is"], k = 4
**Output:** ["the","is","sunny","day"]
**Explanation:** "the", "is", "sunny" and "day" are the four most frequent words, with the number of occurrence being 4, 3, 2 and 1 respectively.
```

**Constraints:**

* `1 <= words.length <= 500`
* `1 <= words[i] <= 10`
* `words[i]` consists of lowercase English letters.
* `k` is in the range `[1, The number of **unique** words[i]]`

**Follow-up:** Could you solve it in `O(n log(k))` time and `O(n)` extra space?

## ac

```java
class Solution {
    public List<String> topKFrequent(String[] words, int k) {
        List<String> res = new ArrayList<>();
        // edge cases
        if (words == null || words.length == 0 || k < 1) return res;

        Map<String, Integer> map = new HashMap<>();
        for (String word : words) {
            map.put(word, map.getOrDefault(word, 0)+1);
        }

        PriorityQueue<Map.Entry<String,Integer>> pq = new PriorityQueue<>((a, b) -> {
            return a.getValue() == b.getValue() ? a.getKey().compareTo(b.getKey()) : b.getValue() - a.getValue();
        });

        for (Map.Entry<String, Integer> e : map.entrySet()) {
            pq.offer(e);
        }

        for (int i = 0; i < k; i++) {
            res.add(pq.poll().getKey());
        }

        return res;
    }
}

// same as https://leetcode.com/problems/top-k-frequent-elements
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://jaywin.gitbook.io/leetcode/solutions/0692-top-k-frequent-words.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.