Algorithm and Program for Merge Short

Algorithm

function merge(left,right)

    var list result

    while length(left) > 0 or length(right) > 0

        if length(left) > 0 and length(right) > 0

            if first(left) ≤ first(right)

                append first(left) to result

                left = rest(left)

            else

                append first(right) to result

                right = rest(right)

        else if length(left) > 0

            append first(left) to result

            left = rest(left)

        else if length(right) > 0

            append first(right) to result

            right = rest(right)

    end while

    return result

Program

#include <stdio.h>
#include<conio.h>
int a[50];
void merge(int,int,int);
void merge_sort(int low,int high)
{ int mid;
  if(low<high)
 {mid=(low+high)/2;
  merge_sort(low,mid);
  merge_sort(mid+1,high);
  merge(low,mid,high);
 }
}

void merge(int low,int mid,int high)
{
 int h,i,j,b[50],k;
 h=low;
 i=low;
 j=mid+1;

 while((h<=mid)&&(j<=high))
 {if(a[h]<=a[j])
  {b[i]=a[h];
   h++;
  }
  else
  {b[i]=a[j];
   j++;
  }
  i++;
 }
 if(h>mid)
 {
  for(k=j;k<=high;k++)
  {b[i]=a[k];
   i++;
  }
 }
 else
 {  for(k=h;k<=mid;k++)
       {b[i]=a[k];
        i++;
       }
 }
 for(k=low;k<=high;k++) a[k]=b[k];
}
int main()
{int num,i;
 printf("Please Enter THE NUMBER OF ELEMENTS you want to sort :\n");
 scanf("%d",&num);
 printf("\n");
 printf("Now, Please Enter the ( %d ) numbers :\n",num);
 for(i=1;i<=num;i++)
 {  scanf("%d",&a[i]); }
 merge_sort(1,num);
 printf("\n");
 printf("So, the sorted list (using MERGE SORT) will be :\n");
 printf("\n\n");
 for(i=1;i<=num;i++)
 printf("%d  ",a[i]);
 printf("\n\n\n\n");
getch();
return 0;
}