Java Coding Test Course, Jumong’s Command

Hello, everyone! Today, I would like to talk about preparing for coding tests using Java. In this lecture, we will solve an algorithm problem with the theme “Jumong’s Command,” which will help enhance our skills in handling arrays and strings, as well as basic algorithm design.

Problem Description

Jumong wants to give commands to 10 warriors and record their performances. Each warrior can deliver different performances each day, and these performances are given in the form of an array. However, Jumong needs to effectively compare and evaluate the warriors’ performances, so he wants to know the best performance among them. Write a program that finds the highest score in the given performance array and records that score.

Problem Specification

Input: An array scores consisting of integers is given. The length of this array is between 1 and 100,000. Each integer is between 0 and 10,000.

Output: Print the highest score in the scores array.

Example

Input: [85, 92, 75, 88, 95, 100, 60]
Output: 100

Problem Solving Process

To solve this problem, we will go through the following steps:

Step 1: Problem Analysis

To find the highest score, we can iterate through the scores array, comparing each score. At this time, we should consider various approaches based on the length of the array.

Step 2: Algorithm Design

We will use the linear search method. This method checks each element once to find the maximum value. The time complexity of this algorithm is O(n), which increases with the size of the input array.

Step 3: Implementing Java Code

Now, let’s implement the algorithm in Java code. Below is an example of how to write the code to solve this problem.

public class JumongCommand {
    public static int findMaxScore(int[] scores) {
        int maxScore = scores[0]; // Initialize the first score as the max score
        for (int i = 1; i < scores.length; i++) {
            if (scores[i] > maxScore) {
                maxScore = scores[i]; // Update if the current score is greater than the max score
            }
        }
        return maxScore; // Return the final maximum score
    }

    public static void main(String[] args) {
        int[] scores = {85, 92, 75, 88, 95, 100, 60};
        int maxScore = findMaxScore(scores);
        System.out.println("The highest score is: " + maxScore); // Print the maximum score
    }
}

Step 4: Testing and Validation

After writing the code, it is necessary to conduct tests with various input values. Below are some test cases.

public static void main(String[] args) {
    // Test case 1
    int[] scores1 = {85, 92, 75, 88, 95, 100, 60};
    System.out.println(findMaxScore(scores1)); // Output: 100

    // Test case 2
    int[] scores2 = {50, 55, 60, 45, 40};
    System.out.println(findMaxScore(scores2)); // Output: 60

    // Test case 3
    int[] scores3 = {100, 100, 100, 100, 100};
    System.out.println(findMaxScore(scores3)); // Output: 100

    // Test case 4 (single value)
    int[] scores4 = {42};
    System.out.println(findMaxScore(scores4)); // Output: 42

    // Test case 5 (empty case)
    int[] scores5 = {};
    try {
        System.out.println(findMaxScore(scores5)); // Exception occurs
    } catch (Exception e) {
        System.out.println("There are no scores."); // Error handling
    }
}

Step 5: Time Complexity Analysis

The time complexity of this algorithm is O(n). This is because it checks each element in the array once, resulting in a time expenditure proportional to the size n of the input array. The space complexity is O(1), as it does not use any additional data structures, thereby maintaining fixed space.

Conclusion

In this lecture, we implemented an algorithm to find the maximum value in an array using Java. I hope this problem has helped you build a foundation in array processing and algorithm design. Next time, we will tackle more complex problems. Thank you!