19_find-missing-in-second-array.java

// 04-2024(April)/19_find-missing-in-second-array.java
/**
 * Date  : 19-Apr-24
 * Repo  : https://github.com/ankitsamaddar/daily-geeksforgeeks
 *
 * Problem   :  Find missing in second array
 * Difficulty:  🟢Easy
 *
 * GeeksforGeeks : https://www.geeksforgeeks.org/problems/in-first-but-second5423/1
 */

import java.io.*;
import java.util.*;

// User function Template for Java

class Solution {
  ArrayList<Integer> findMissing(int a[], int b[], int n, int m) {
    HashSet<Integer> set = new HashSet<>();
    // Hash elements of the second array to the set
    for (int i = 0; i < m; i++) {
      set.add(b[i]);
    }

    ArrayList<Integer> missingElements = new ArrayList<>();

    // Iterate the first array and store missing elements in second array
    for (int i = 0; i < n; i++) {
      if (!set.contains(a[i])) {
        missingElements.add(a[i]);
      }
    }

    return missingElements;
  }
}

//{ Driver Code Starts.


//{ Driver Code Starts
// Initial Template for Java
// Driver class
class Array {
  // Driver code
  public static void main(String[] args) throws IOException {
    // Taking input using buffered reader
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    int testcases = Integer.parseInt(br.readLine());
    // looping through all testcases
    while (testcases-- > 0) {
      //            int n = Integer.parseInt(br.readLine());
      String line = br.readLine();
      String[] q  = line.trim().split("\\s+");
      int n       = Integer.parseInt(q[0]);
      int m       = Integer.parseInt(q[1]);
      // int y =Integer.parseInt(q[2]);
      String line1 = br.readLine();
      String[] a1  = line1.trim().split("\\s+");
      int a[]      = new int[n];
      for (int i = 0; i < n; i++) {
        a[i] = Integer.parseInt(a1[i]);
      }
      String line2 = br.readLine();
      String[] a2  = line2.trim().split("\\s+");
      int b[]      = new int[m];
      for (int i = 0; i < m; i++) {
        b[i] = Integer.parseInt(a2[i]);
      }
      Solution ob            = new Solution();
      ArrayList<Integer> ans = ob.findMissing(a, b, n, m);
      for (int i = 0; i < ans.size(); i++) {
        System.out.print(ans.get(i) + " ");
      }
      System.out.println();
    }
  }
}

// } Driver Code Ends