Merge sort

Sorting is arranging the elements into increasing or decreasing order.
Merge sort is one of the fast sorting algorithm . It is a Divide and Conquer algorithm. It divides the input array into two halves, calls itself for the two halves, and then merges the two sorted halves The sub-lists are divided again and again into halves until the list cannot be divided further. Then we combine the pair of one element lists into two-element lists, sorting them in the process. The sorted two-element pairs is merged into the four-element lists, and so on until we get the sorted list.We have define the merge() function to merge the two halves.
//Code in C on merge sort

#include<stdio.h>
int b[10][arr[10];
/* merge function */
void merge(int low,int mid ,int high)
{
 int i=low;
 int j=mid+1;
 int h=low;
 int k;
 while((h<=mid) &&(j<=high))
  {
  if(arr[h]<=arr[j])
  {
   b[i]=arr[h];
   h=h+1;
  }
  else
  {
    b[i]=arr[j];
    j=j+1;
  }
  i=i+1;
  }
 if(h>mid) 
 {
  for(k=j;k<=high;k++)
    {
    b[i]=arr[k];
    i=i+1;
    }
 } 
 else
  for(k=h;k<=mid;k++)
  {
   b[i]=arr[k];
   i=i+1;
  } 
  for(k=low;k<=high;k++)
  {
    arr[k]=b[k];
  }
}  
/* mergesort function */
void mergesort(int low,int high)
{
 int i;
 if(low<high)
 {
  int mid;
  mid=(low+high)/2;
  mergesort(low,mid);
  mergesort(mid+1,high);
  merge(low,mid,high);
 }
 for(i=low;i<=high;i++)
 {
   printf("%d",arr[i]);
 }
}

//Main function
void main()
{
  int i,n,j;
  printf("Enter no of element in an array");
  scanf("%d",&n);
  printf("Enter %d elements ",n);
  for(i=0;i<n;i++)
   {
    scanf("%d",arr[i]);
   }
  for(j=0;j<=n-1;j++)
  {
    printf("%d",arr[j]);
  }
  
  mergesort(0,n-1);
 }
/*Code end*/
Output
 Enter no. of element
 5
 Enter elements
 2 9 6 1 0
 printf("Elements after sorting are:");
 0 1 2 6 9
  
//Time Complexity of merge sort
  Best case :It occur when array is already sorted .The time complexity in this case is O(nlogn)
  Average case :O(nlogn)
  Worst case:O(nlogn)
//Space complexity of merge sort
  The space complexity of merge sort is O(n). It is because, in merge sort, an extra variable is required for swapping.