Advanced Map: Word Frequency Counter

020-004-001

Advanced Map: Word Frequency Counter

Hard

Problem Description

In this problem, you will create a program that receives a list of words as input, counts the frequency of each word using HashMap.merge(), sorts the results in descending order by frequency (alphabetical order for ties), and displays the result to standard output.

Frequency Counting Pattern

Learn efficient counting using HashMap.getOrDefault() and merge().

Counting method

Map<String, Integer> freq = new HashMap<>();
For (String word : words) {
    Freq.merge(word, 1, Integer::sum);
}

Sorting Method

List<Map.Entry<String, Integer>> entries = new ArrayList<>(freq.entrySet());
Entries.sort((a, b) -> {
    Int cmp = b.getValue().compareTo(a.getValue()); // descending
    Return cmp != 0 ? Cmp : a.getKey().compareTo(b.getKey()); // alphabetical if same
});

Learning Points

merge() uses initial value if key missing, applies function if exists
Comparator chaining achieves compound sort conditions
entrySet() retrieves key-value pairs together

Test Cases

※ Output examples follow programming industry standards

Normal case

Input:

7
apple banana apple orange banana apple grape

Expected Output:

apple: 3
banana: 2
grape: 1
orange: 1

Boundary case

Input:

5
cat cat cat cat cat

Expected Output:

cat: 5

Your Solution

Current Mode:● My Code

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    // Write your code here

    sc.close();
  }
}

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