using System;

public class Program

{

    public static void Main()

    {

        int[] arr = null;      // declaring array

            arr = new int[10];   // memory allocation

            Console.Write("Before remove even: ");

            for (int i = 0; i < 10; i++)

            {

                arr[i] = i;      // assigning values

                Console.Write(arr[i] + " ");

            }

            Console.WriteLine("");

            arr = removeEven(arr, 10);   // calling removeEven

            Console.Write("After remove even: ");

            for (int i = 0; i < 5; i++)

            {

                Console.Write( arr[i] + " ");    // prinitng array

            }

            Console.WriteLine(""); 

            return ;

    }

    //Implement a function removeEven( int[]Arr, int size ), which takes an array arr and its size and removes all the even elements from the given array.

    //Explanation

    //This solution starts with the first element of the given array: Arr checks if it is odd. 

    //Then it moves this element to the start of the array Arr if it is odd; otherwise, it jumps to the next element. 

    //This repeats until the end of the array Arr is reached while keeping the count of total odd numbers m in Arr. 

    //Next, make a temporary array to store all odd numbers in: temp. Point Arr to the temp array. No variable is referencing to the array that Arr was previously referencing, so the Garbage collector will collect that array later in time, freeing up the memory. Lastly, return the array Arr, that is, containing only odd elements only.

    //Time complexity

    //Since the entire array has to be iterated over, this solution works in O(n)

     public static int[] removeEven(int[] Arr, int size)

    {

        int m = 0;

        for (int i = 0; i < size; i++)

        {

            if (Arr[i] % 2 != 0)  // if odd number found

            {

                Arr[m] = Arr[i];   //inserting odd values in array

                ++m;

            }

        }

        int[] temp = new int[m];

        for (int i = 0; i < m; i++)

            temp[i] = Arr[i];

​

        Arr = temp;

        return Arr;  // returning array after removing odd numbers

    }

}