Java Coding Test Course, Dictionary Search

Problem Description

You have a dictionary consisting of several words. You need to create a program that checks if a specific word exists in this dictionary
and outputs the meaning of that word.

The input consists of a list of words in the dictionary and a word entered by the user. If the word entered by the user is
not in the dictionary, it should output the message “The word could not be found.”

Input Details

• The first line contains an integer N (1 ≤ N ≤ 100,000).
• The next N lines contain the words in the dictionary.
• The last line contains the word that the user wants to search for.

Output Details

Output the meaning of the word entered by the user, but if the word is not found in the dictionary, output “The word could not be found.”

Examples

Input:
5
apple
banana
grape
orange
pear
grape

Output:
"grape": grape

Input:
5
apple
banana
grape
orange
pear
watermelon

Output:
The word could not be found.

Problem Solving Strategy

This problem requires searching for a word, so choosing an efficient data structure is key.
Using a HashMap allows you to search for a word with an average time complexity of O(1).
Therefore, you can store the dictionary in a HashMap, then search for the word entered by the user in that HashMap
to output its meaning.

Java Code Implementation

Below is the Java code to solve the above problem. This code implements the dictionary using a HashMap and handles user input.

import java.util.HashMap;
import java.util.Scanner;

public class DictionarySearch {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        
        // Input the number of words in the dictionary
        int N = scanner.nextInt();
        scanner.nextLine(); // Remove the newline character
        
        // Initialize the HashMap
        HashMap dictionary = new HashMap<>();
        
        // Input words and meanings for the dictionary
        for (int i = 0; i < N; i++) {
            String word = scanner.nextLine(); // Input word
            String meaning = scanner.nextLine(); // Input meaning
            dictionary.put(word, meaning);
        }
        
        // Input the word to search
        String searchWord = scanner.nextLine();
        
        // Search for the word and output the result
        if (dictionary.containsKey(searchWord)) {
            System.out.println("\"" + searchWord + "\": " + dictionary.get(searchWord));
        } else {
            System.out.println("The word could not be found.");
        }

        scanner.close();
    }
}

Code Explanation

1. The Scanner class is used to handle user input, and HashMap is used to store the dictionary.
2. First, the size of the dictionary N is input, and then words and their meanings are added to the HashMap for N times.
3. Next, the user inputs the word they want to search for, and it checks if that word is in the HashMap.
4. If the word exists, its meaning is printed; if not, the message "The word could not be found." is printed.

Complexity Analysis

- Time Complexity: O(1) for adding a word to the HashMap and O(1) for searching. Overall O(N).
- Space Complexity: O(N) as the HashMap stores N words and their meanings.

Conclusion

In this article, we looked at an algorithm problem to find a specific word in a dictionary using Java.
We learned how to efficiently search for words using a HashMap and gained insights into what approach to take
during coding tests through the problem-solving process.
I hope you can confidently solve similar problems in future coding tests.