Find first repeating element in array

Here given code implementation process.

// C++ Program 
// Find first repeating element in array
#include <iostream>
#include <set>

using namespace std;

// Find the first element of array which are repeated from left to right
void firstRepeating(int arr[], int size)
{
    // Define a empty set
    set < int > data;

    bool status = false;
    int result = 0;

    // Execute loop through by array size
    for (int i = size-1; i >=  0; --i)
    {
        if(data.find(arr[i]) == data.end())
        {
            data.insert(arr[i]); 
        }
        else
        {
            // When get a new result
            result = arr[i];
            status = true;
        }

    }
    if (status == false)
    {
        cout << "None" << endl;
    }
    else
    {
        cout << result <<endl;
    }
}
int main()
{
    // Define array of integer element
    int arr[] = 
    {
        3 , 9 , 7 , 6,  7 , 2 , 9 , 1 , 7 , 6
    };
    // Get the size of array
    int size = sizeof(arr) / sizeof(arr[0]);
    
    firstRepeating(arr, size);
    return 0;
}

Output

9
/*
   Java program
   Find first repeating element in array
*/
import java.util.HashSet;
public class Counting
{
	// Find the first element of array which are repeated from left to right
	public void firstRepeating(int[] arr)
	{
		// This is used to collect result
		int result = 0;
		// Result indicator
		boolean status = false;
		// Create a empty hashSet
		HashSet <Integer> data = new HashSet<>();
		// iterate through  by array size
		for (int i = arr.length - 1; i > 0; --i)
		{
			if (data.contains(arr[i]))
			{
				// When elements are already exists
				status = true;
				result = arr[i];
			}
			else
			{
				// When inserting new element
				data.add(arr[i]);
			}
		}
		if (status == true)
		{
			// When result exists
			System.out.print(result);
		}
		else
		{
			// When result not exists
			System.out.print(" None \n");
		}
	}
	public static void main(String[] args)
	{
		Counting task = new Counting();
		// Get the size of array
		int[] arr = {
			3 , 9 , 7 , 6 , 7 , 2 , 9 , 1 , 7 , 6
		};
		task.firstRepeating(arr);
	}
}

Output

9
// Include namespace system
using System;
using System.Collections.Generic;
public class Counting
{
	// Find the first element of array which are repeated from left to right
	public void firstRepeating(int[] arr)
	{
		// This is used to collect result
		int result = 0;
		// Result indicator
		Boolean status = false;
		// Create a empty hashSet
		HashSet <int> data = new HashSet <int> ();
		// iterate through  by array size
		for (int i = arr.Length - 1; i > 0; --i)
		{
			if (data.Contains(arr[i]))
			{
				// When elements are already exists
				status = true;
				result = arr[i];
			}
			else
			{
				// When inserting new element
				data.Add(arr[i]);
			}
		}
		if (status == true)
		{
			// When result exists
			Console.Write(result);
		}
		else
		{
			// When result not exists
			Console.Write(" None \n");
		}
	}
	public static void Main(String[] args)
	{
		Counting task = new Counting();
		// Get the size of array
		int[] arr = {
			3 , 9 , 7 , 6 , 7 , 2 , 9 , 1 , 7 , 6
		};
		task.firstRepeating(arr);
	}
}

Output

9
<?php
// Php Program 
// Find first repeating element in array
class Counting
{
	// Find the first element of array which are repeated from left to right
	public	function firstRepeating( & $arr)
	{
		// This is used to collect result
		$result = 0;
		// Result indicator
		$status = false;
		// Create a empty array
		$data = [];
		// iterate through  by array size
		for ($i = count($arr) - 1; $i > 0; --$i)
		{
			if (array_key_exists($arr[$i],$data))
			{
				// When elements are already exists
				$status = true;
				$result = $arr[$i];
			}
			else
			{
				// When inserting new element
				$data[$arr[$i]]=1;
			}
		}
		if ($status == true)
		{
			// When result exists
			echo $result;
		}
		else
		{
			// When result not exists
			echo " None \n";
		}
	}
}

function main()
{
	$task = new Counting();
	// Get the size of array
	$arr = array(3, 9, 7, 6, 7, 2, 9, 1, 7, 6);
	$task->firstRepeating($arr);
}
main();

Output

9
class Counting
{
	// Find the first element of array which are repeated from left to right
	firstRepeating(arr)
	{
		// This is used to collect result
		var result = 0;
		// Result indicator
		var status = false;
		// Create a empty Set
		
		var data = new Set();;
		// iterate through  by array size
		for (var i = arr.length - 1; i > 0; --i)
		{
			if (data.has(arr[i]))
			{
				// When elements are already exists
				status = true;
				result = arr[i];
			}
			else
			{
				// When inserting new element
				data.add(arr[i]);
			}
		}
		if (status == true)
		{
			// When result exists
			console.log(result);
		}
		else
		{
			// When result not exists
			console.log(" None \n");
		}
	}
}

function main()
{
	var task = new Counting();
	// Get the size of array
	var arr = [3, 9, 7, 6, 7, 2, 9, 1, 7, 6];
	task.firstRepeating(arr);
}
main();

Output

9
#    Python 3 program
#    Find first repeating element in array

class Counting :
	#  Find the first element of list which are repeated from left to right
	def firstRepeating(self, arr) :
		#  This is used to collect result
		result = 0
		#  Result indicator
		status = False
		#  Create a empty Set
		data = set()
		i = len(arr) - 1
		#  iterate through  by list size
		while (i > 0) :
			if (arr[i] in data) :
				#  When elements are already exists
				status = True
				result = arr[i]
			else :
				#  When inserting new element
				data.add(arr[i])
			
			i -= 1
		
		if (status == True) :
			#  When result exists
			print(result, end = "")
		else :
			#  When result not exists
			print(" None ")
		
	

def main() :
	task = Counting()
	#  Get the size of list
	arr = [3, 9, 7, 6, 7, 2, 9, 1, 7, 6]
	task.firstRepeating(arr)

if __name__ == "__main__": main()

Output

9
#    Ruby program
#    Find first repeating element in array

class Counting 
	#  Find the first element of array which are repeated from left to right
	def firstRepeating(arr) 
		#  This is used to collect result
		result = 0
		#  Result indicator
		status = false
		#  Create a empty array
		data = []
		i = arr.length - 1
		#  iterate through  by array size
		while (i > 0) 
			if (data.include? (arr[i])) 
				#  When elements are already exists
				status = true
				result = arr[i]
			else 
				#  When inserting new element
				data.push(arr[i])
			end

			i -= 1
		end

		if (status == true) 
			#  When result exists
			print(result)
		else 
			#  When result not exists
			print(" None \n")
		end

	end

end

def main() 
	task = Counting.new()
	#  Get the size of array
	arr = [3, 9, 7, 6, 7, 2, 9, 1, 7, 6]
	task.firstRepeating(arr)
end

main()

Output

9
import scala.collection.mutable._ ;
/*
   Scala program
   Find first repeating element in array
*/
class Counting
{
	// Find the first element of array which are repeated from left to right
	def firstRepeating(arr: Array[Int]): Unit = {
		// This is used to collect result
		var result: Int = 0;
		// Result indicator
		var status: Boolean = false;
		// Create a empty Set
		var data : Set[Int] = Set();

		var i: Int = arr.length - 1;
		// iterate through  by array size
		while (i > 0)
		{
			if (data.contains(arr(i))==true)
			{
				// When elements are already exists
				status = true;
				result = arr(i);
			}
			else
			{
				// When inserting new element
				data.add(arr(i));
			}
			i -= 1;
		}
		if (status == true)
		{
			// When result exists
			print(result);
		}
		else
		{
			// When result not exists
			print(" None \n");
		}
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var task: Counting = new Counting();
		// Get the size of array
		var arr: Array[Int] = Array(3, 9, 7, 6, 7, 2, 9, 1, 7, 6);
		task.firstRepeating(arr);
	}
}

Output

9
/*
   Swift 4 program
   Find first repeating element in array
*/
class Counting
{
	// Find the first element of array which are repeated from left to right
	func firstRepeating(_ arr: [Int])
	{
		// This is used to collect result
		var result: Int = 0;
		// Result indicator
		var status: Bool = false;
		// Create a empty Set
		var data = Set<Int>()
		var i: Int = arr.count - 1;
		// iterate through  by array size
		while (i > 0)
		{
			if (data.contains(arr[i]))
			{
				// When elements are already exists
				status = true;
				result = arr[i];
			}
			else
			{
				// When inserting new element
				data.insert(arr[i]);
			}
			i -= 1;
		}
		if (status == true)
		{
			// When result exists
			print(result, terminator: "");
		}
		else
		{
			// When result not exists
			print(" None ");
		}
	}
}
func main()
{
	let task: Counting = Counting();
	// Get the size of array
	let arr: [Int] = [3, 9, 7, 6, 7, 2, 9, 1, 7, 6];
	task.firstRepeating(arr);
}
main();

Output

9
/*
   Kotlin program
   Find first repeating element in array
*/
class Counting
{
	// Find the first element of array which are repeated from left to right
	fun firstRepeating(arr: Array < Int > ): Unit
	{
		// This is used to collect result
		var result: Int = 0;
		// Result indicator
		var status: Boolean = false;
		// Create a empty Set
		var data: MutableSet < Int > = mutableSetOf < Int > ();
		var i: Int = arr.count() - 1;
		// iterate through  by array size
		while (i > 0)
		{
			if (data.contains(arr[i]))
			{
				// When elements are already exists
				status = true;
				result = arr[i];
			}
			else
			{
				data.add(arr[i]);
			}
			i -= 1;
		}
		if (status == true)
		{
			// When result exists
			print(result);
		}
		else
		{
			// When result not exists
			print(" None \n");
		}
	}
}
fun main(args: Array < String > ): Unit
{
	var task: Counting = Counting();
	// Get the size of array
	var arr: Array < Int > = arrayOf(3, 9, 7, 6, 7, 2, 9, 1, 7, 6);
	task.firstRepeating(arr);
}

Output

9


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