Find Unique

 

You have been given an integer array/list(ARR) of size N. Where N is equal to [2M + 1].

Now, in the given array/list, 'M' numbers are present twice and one number is present only once.

You need to find and return that number which is unique in the array/list.

Sample Input 1:

7
2 3 1 6 3 6 2

Sample Output 1:

1

Approach 1 - > (Using XOR)

package CodingNinjas;

import java.util.Scanner;

public class FindUnique {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int n=s.nextInt();
		int a[]=new int[n];
		for(int i=0;i<n;i++)
		{
			a[i]=s.nextInt();
		}
		
		int b= findUnique(a);
		System.out.println(b);
	}
	
	public static int findUnique(int[] arr){
		
		int l=arr.length;
		int ele=0;
		for(int i=0;i<l;i++)
		{

                // if we do XOR of same elements we get 0 i.e 5^5 => 101 ^ 101 = 000 
			ele^=arr[i];
		}

		return ele;
	}

}

Approach 2 - 

public static int findUnique(int[] arr){

int l= arr.length;
		
		for(int i=0;i<l;i++)
		{
			int j;
			for(j=0;j<l;j++)
			{
				if(i!=j)
				{
					if(arr[i]==arr[j])
					{
						break;
					}
				}
			}
			if(j==l)
			{
				return arr[i];
			}
			
		}
		return Integer.MAX_VALUE;
	}
}