Merge_sort.cs

/*
This is implementation of Merge Sort in C#
Merge Sort is a Divide and Conquer algorithm. 
It divides input array in two halves, calls itself for the two halves and then merges the two sorted halves. 
The conquer_merge() function is used for merging two halves.
*/

using System;
public class Merge_Sort
{
    public static int[] temp;
    // Conquer
    public static void conquer_merge(int[] array, int left, int right, int mid)
    {
        int k = left, i, j;

        for(i = left, j = mid + 1; i <= mid && j <= right; k++)
        {
            if(array[i] <= array[j])
            {
                temp[k] = array[i];
                i++;
            }
            else
            {
                temp[k] = array[j];
                j++;
            }
        }

        while(i <= mid)
        {
            temp[k] = array[i];
            i++;
            k++;
        }

        while(j <= right)
        {
            temp[k] = array[j];
            j++;
            k++;
        }

        for(i = left; i <= right; i++)
            array[i] = temp[i];
    }

    // Divide array into halves
    public static void divide(int[] array, int left, int right)
    {
        if(left < right)
        {
            int mid = left + (right - left) / 2;

            divide(array, left, mid);
            divide(array, mid + 1, right);

            conquer_merge(array, left, right, mid);
        }
    }

    public static void MergeSort(int[] array, int size)
    {
        temp = new int[size];
        divide(array, 0, size - 1);
        temp = null;
    }

    // function ro print array
    public static void Print_Array(int[] array, int size)
    {
        for(int i = 0; i < size; i++)
            Console.Write(array[i] + " ");

        Console.Write("");
    }

    public static void Main()
    {
        int size;
        size= Convert.ToInt32(Console.ReadLine()); 

        int[] array = new int[size];

        for(int i=0; i<size; i++)  
	        array[i] = Convert.ToInt32(Console.ReadLine());  		
    
        MergeSort(array, size);
        Print_Array(array, size);
    }
}
// input 
// 7
// 6 2 1 3 4 8 4

// Output
// 1 2 3 4 4 6 8