Thread: merge sort

i am having a problem with the below problem of merge sort, i am not getting a desired ouput.
here is the program

Code:

/* sorting implementing the technique of merge sort */
# include<stdio.h>
# include<conio.h>
void mergesort(int *,int);
void main()
{
int x[20];int i,n;
clrscr();
printf("enter the number of elements of the array ");
scanf("%d",&n);
printf("enter the elemnts");
for(i=0;i<n;i++)
	scanf("%d",&x[i]);
mergesort(x,n);
printf("the sorted elements are\n ");
for(i=0;i<n;i++)
{
	printf("%d",x[i]);
	printf("\n");
}
getch();
}
void mergesort(int x[],int n)
{
	int aux[20],i,j,k,l1,l2,u1,u2;
	int size=1;
	while(size<n)
	{
		l1=0;
		k=0;
		while(l1+size<n)
		{
			l2=l1+size;
			u2=l2-1;
			u2=(l2+size-1)? l2+size-1:n-1;
			for(i=l1,j=l2;i<=u1&&j<=u2;k++)
				if(x[i]<=x[j])
					aux[k]=x[i++];
				else
					aux[k]=x[j++];
			for(;i<=u1;k++)
				aux[k]=x[i++];
			for(;j<=u2;k++)
				aux[k]=x[j++];
			l2=u2+1;
		 }
		for(i=l1;k<n;i++)
			aux[k++]=x[i];
		for(i=0;i<n;i++)
			x[i]=aux[i];
		size*=2;
 }
 }

every time the program runs,it intakes the values then getting out of the dos shell.


[code][/code]tagged by Salem

Few people will be able to understand this. Why don't you
just code it like this

Code:

void mergesort(int A[], int p, int r) {
        if (p < r)  {
              int q = (r - p)/ 2;
              mergesort(p, q);
              mergesort(q + 1, r);
              merge(A, p, q, r);
        }
}

// merge the sorted A[p..q] with A[q + 1..r] to make
// a sorted A[p..r]
void merge(int A[], int p, int q, int r) {
// code for merge

}

int q = (r - p)/ 2;
This should be (r + p) / 2;