Java: Find common elements from three sorted arrays

Write a Java program to find common elements in three sorted (in non-decreasing order) arrays.

Pictorial Presentation:

Sample Solution:

Java Code:

// Import the java.util package to use utility classes, including ArrayList.
import java.util.*;

// Define a class named Exercise25.
public class Exercise25 {
    // The main method for executing the program.
    public static void main(String[] args) {
        // Create an ArrayList to store common elements.
        ArrayList common = new ArrayList();

        // Declare three arrays of integers.
        int array1[] = {2, 4, 8};
        int array2[] = {2, 3, 4, 8, 10, 16};
        int array3[] = {4, 8, 14, 40};

        // Initialize three index variables for each array.
        int x = 0, y = 0, z = 0;

        // Use a while loop to compare elements of the three arrays.
        while (x < array1.length && y < array2.length && z < array3.length) {
            // Check if the elements at the current positions in all arrays are equal.
            if (array1[x] == array2[y] && array2[y] == array3[z]) {
                // If they are equal, add the element to the 'common' ArrayList and increment all indices.
                common.add(array1[x]);
                x++;
                y++;
                z++;
            } else if (array1[x] < array2[y]) {
                // If the element in the first array is smaller, increment the index of the first array.
                x++;
            } else if (array2[y] < array3[z]) {
                // If the element in the second array is smaller, increment the index of the second array.
                y++;
            } else {
                // If the element in the third array is smaller, increment the index of the third array.
                z++;
            }
        }

        // Print the common elements found in the three sorted arrays.
        System.out.println("Common elements from three sorted (in non-decreasing order) arrays: ");
        System.out.println(common);
    }
}

Sample Data: array1 = 2, 4, 8
array2 = 2, 3, 4, 8, 10, 16
array3 = 4, 8, 14, 40

Sample Output:

                                                                              
Common elements from three sorted (in non-decreasing order ) arrays:   
[4, 8]

Flowchart:

Java Code Editor:

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