Find common elements in three sorted arrays

/*package whatever //do not write package name here */

import java.io.*;

public class GFG {

    // Function to find the intersection of two arrays
    static void findIntersection(int[] arr1, int[] arr2,
                                 int[] temp, int m, int n,
                                 int[] k)
    {
        int i = 0, j = 0;
        // Loop to find the intersection of arr1[] and
        // arr2[]
        while (i < m && j < n) {
            // ith element can't be a common element
            if (arr1[i] < arr2[j]) {
                i++;
            }
            // jth element can't be a common element
            else if (arr2[j] < arr1[i]) {
                j++;
            }
            // if arr1[i] == arr2[j]
            else {
                temp[k[0]] = arr1[i];
                i++;
                j++;
                k[0]++;
            }
        }
    }

    public static void main(String[] args)
    {

        int[] arr1 = { 1, 5, 10, 20, 40, 80 };
        int[] arr2 = { 6, 7, 20, 80, 100 };
        int[] arr3 = { 3, 4, 15, 20, 30, 70, 80, 120 };
        int n1 = arr1.length;
        int n2 = arr2.length;
        int n3 = arr3.length;

        // temp array to store the common elements of arr1
        // and arr2 arrays
        int[] temp = new int[200000];

        // ans array to store the common elements of temp
        // and arr3 arrays
        int[] ans = new int[200000];

        int[] k = {
            0
        }; // Mutable integer to simulate pass-by-reference

        // function call to find the temp array
        findIntersection(arr1, arr2, temp, n1, n2, k);
        int tempSize = k[0];
        k[0] = 0;

        // function call to find the ans array
        findIntersection(arr3, temp, ans, n3, tempSize, k);

        System.out.println(
            "Common elements present in arrays are :");

        // Printing the common elements
        for (int i = 0; i < k[0]; i++) {
            System.out.print(ans[i] + " ");
        }
        System.out.println();
    }
}

// Java program to find common elements in three arrays
import java.io.*;
class FindCommon {
    // This function prints common elements in ar1
    void findCommon(int ar1[], int ar2[], int ar3[])
    {
        // Initialize starting indexes for ar1[], ar2[] and
        // ar3[]
        int i = 0, j = 0, k = 0;

        // Iterate through three arrays while all arrays
        // have elements
        while (i < ar1.length && j < ar2.length
               && k < ar3.length) {
            // If x = y and y = z, print any of them and
            // move ahead in all arrays
            if (ar1[i] == ar2[j] && ar2[j] == ar3[k]) {
                System.out.print(ar1[i] + " ");
                i++;
                j++;
                k++;
            }

            // x < y
            else if (ar1[i] < ar2[j])
                i++;

            // y < z
            else if (ar2[j] < ar3[k])
                j++;

            // We reach here when x > y and z < y, i.e., z
            // is smallest
            else
                k++;
        }
    }

    // Driver code to test above
    public static void main(String args[])
    {
        FindCommon ob = new FindCommon();

        int ar1[] = { 1, 5, 10, 20, 40, 80 };
        int ar2[] = { 6, 7, 20, 80, 100 };
        int ar3[] = { 3, 4, 15, 20, 30, 70, 80, 120 };

        System.out.print("Common elements are ");
        ob.findCommon(ar1, ar2, ar3);
    }
}

/*This code is contributed by Rajat Mishra */

import java.util.ArrayList;
import java.util.List;

public class Main {
    public static List<Integer> findCommonElements(List<Integer> ar1,
                                                   List<Integer> ar2,
                                                   List<Integer> ar3) {
        List<Integer> ref = new ArrayList<>();
        List<Integer> finalList = new ArrayList<>();

        // Step 1: Iterate through ar1
        for (int num : ar1) {
            // Step 2: Check if num exists in ar2
            if (ar2.contains(num)) {
                // If found, append it to the reference list
                ref.add(num);
            }
        }

        // Step 3: Iterate through the reference list
        for (int num : ref) {
            // Step 4: Check if num exists in ar3
            if (ar3.contains(num)) {
                // If found, append it to the final list
                finalList.add(num);
            }
        }

        return finalList;
    }

    public static void main(String[] args) {
        List<Integer> ar1 = List.of(1, 5, 10, 20, 40, 80);
        List<Integer> ar2 = List.of(6, 7, 20, 80, 100);
        List<Integer> ar3 = List.of(3, 4, 15, 20, 30, 70, 80, 120);

        List<Integer> finalList = findCommonElements(ar1, ar2, ar3);

        for (int num : finalList) {
            System.out.print(num + " ");
        }
        System.out.println();
    }
}