findDuplicate.java

/*Find Duplicate
You have been given an integer array/list(ARR) of size N which contains numbers from 0 to (N - 2). Each number is present at least once. That is, if N = 5, the array/list constitutes values ranging from 0 to 3 and among these, there is a single integer value that is present twice. You need to find and return that duplicate number present in the array.*/


package Array_1D;

import java.util.Scanner;

public class findDuplicate 
{
	public static int duplicateNumber(int[] arr)
	{
		for(int i=0;i<arr.length;i++)
		{
			for(int j=i+1;j<arr.length;j++)
			{
				if(arr[i]==arr[j])
				{
					System.out.print("Duplicate Value : ");
					return arr[i];
				}
			}
		}
		return -1;
	}
	
	public static void printArray(int arr[])
	{
		for(int i= 0; i<arr.length; i++)
		{
			System.out.print(arr[i]+ ", ");
		}
		System.out.println();
	}
	
	public static void main(String[] args) 
	{
		Scanner sc = new Scanner(System.in);
		System.out.print("Enter the size of array : ");
		int size = sc.nextInt();
		int[] input_arr = new int[size];
		for(int i= 0; i<size; i++)
		{
			System.out.print("Enter the element at "+ i + "th term : ");
			input_arr[i] = sc.nextInt();
		}
		printArray(input_arr);
		int duplicate_value = duplicateNumber(input_arr);
		System.out.println(duplicate_value);
	}
}