https://www.hackerrank.com/challenges/missing-numbers

missingNumbers.java

import java.util.Iterator;
import java.util.Scanner;
import java.util.Map;
import java.util.HashMap;
import java.util.TreeSet;

public class missingNumbers {

	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int n=sc.nextInt();
		HashMap<Integer, Integer> nrr=new HashMap<Integer, Integer>();
		
		for(int i=0;i<n;++i){
			int x=sc.nextInt();
			if(nrr.containsKey(x)){
				int val = nrr.get(x);
				nrr.put(x, val+1);
			}
			else{
				nrr.put(x, 1);
			}
		}
		
    
		int m=sc.nextInt();
		HashMap<Integer, Integer> mrr=new HashMap<Integer, Integer>();
		
		for(int i=0;i<m;++i){
			int x=sc.nextInt();
			if(mrr.containsKey(x)){
				int val = mrr.get(x);
				mrr.put(x, val+1);
			}
			else{
				mrr.put(x, 1);
			}
		}
		
    
		TreeSet<Integer> ts = new TreeSet<Integer>();
		
		for(Map.Entry<Integer, Integer> a : mrr.entrySet()){
			int keyX = a.getKey();
			int valM = a.getValue();
			if(nrr.containsKey(keyX)==false){
				ts.add(keyX);
			}
			else if(nrr.containsKey(keyX)==true){
				int valN = nrr.get(keyX);
				if(valM != valN){
					ts.add(keyX);
				}
			}
		}
		
    
		Iterator it = ts.iterator();
		while(it.hasNext()){
			System.out.print(it.next()+" ");
		}	
	}
}