Problem Statement
Word Frequency Analyzer
You're building a text analysis tool that needs to identify the most commonly used words in a document.
Given a non-empty array of strings words, return the k most frequent elements.
Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first.
Examples
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].length <= 10
- words[i] consists of lowercase English letters
- k is in the range [1, the number of unique words[i]]
Problem Breakdown
To solve this problem, we need to:
- We need to count the frequency of each word in the array
- Words with higher frequencies should appear before words with lower frequencies
- If two words have the same frequency, they should be sorted alphabetically
- A hash map or frequency counter is useful for tracking word frequencies
- A priority queue (heap) can efficiently find the k most frequent elements
- The problem can also be solved by sorting all words by their frequencies
String Problems
Learning Objective
Apply string manipulation concepts to solve a real-world problem.
Word Frequency Analyzer
You're building a text analysis tool that needs to identify the most commonly used words in a document.
Given a non-empty array of strings words, return the k most frequent elements.
Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first.
Examples
Example 1:
"i" and "love" are the two most frequent words. Note that "i" comes before "love" due to a lower alphabetical order.
Example 2:
"the", "is", "sunny" and "day" are the four most frequent words, with the number of occurrence being 4, 3, 2 and 1 respectively.
Problem Breakdown
Constraints:
- 1 <= words.length <= 500
- 1 <= words[i].length <= 10
- words[i] consists of lowercase English letters
- k is in the range [1, the number of unique words[i]]
Key Insights:
We need to count the frequency of each word in the array
Words with higher frequencies should appear before words with lower frequencies
If two words have the same frequency, they should be sorted alphabetically
A hash map or frequency counter is useful for tracking word frequencies
A priority queue (heap) can efficiently find the k most frequent elements
The problem can also be solved by sorting all words by their frequencies
Real-World Application
This problem has several practical applications:
Text Analysis
Identifying the most common words in documents for content analysis or summarization.
Search Engine Optimization
Analyzing keyword frequency to improve search engine rankings.
Content Recommendation
Building recommendation systems based on frequently used terms in user preferences.
Data Mining
Extracting meaningful patterns from large text datasets by identifying common terms.