Source Code
#include<stdlib.h>
#include<stdio.h>
void merge(int *list, int l, int m, int r)
{
int i, j, k;
int n1 = m - l + 1;
int n2 = r - m;
/* create temp arrays */
int L[n1], R[n2];
/* Copy data to temp arrays L[] and R[] ;
Basically L[] denotes the left subarray and R[] denotes right subarray*/
for (i = 0; i < n1; i++)
L[i] = list[l + i];
for (j = 0; j < n2; j++) /*divide method for divide and conquer algorithm*/
R[j] = list[m + 1+ j];
/* Merge the temp arrays back into arr[l..r]*/
i = 0; // Initial index of first subarray
j = 0; // Initial index of second subarray
k = l; // Initial index of merged subarray
while (i < n1 && j < n2)
{
if (L[i] <= R[j])
{
list[k] = L[i];
i++; /*place the elements in their exact position based on comparisions*/
} /*conquer method which is basically combine*/
else
{
list[k] = R[j];
j++;
}
k++;
}
/* Copy the remaining elements of L[], if there are any */
while (i < n1)
{
list[k] = L[i];
i++;
k++;
}
/* Copy the remaining elements of R[], if there
are any */
while (j < n2)
{
list[k] = R[j];
j++;
k++;
}
}
/* l is for left index and r is right index of the
sub-array of arr to be sorted */
void mergesort(int *list, int l, int r)
{
if (l < r)
{
// Same as (l+r)/2, but avoids overflow for large l and h
int m = l+(r-l)/2;
// Sort first and second halves
mergesort(list, l, m);
mergesort(list, m+1, r);
merge(list, l, m, r);
}
}
void display(int *list, int size)
{
int i;
for (i=0; i < size; i++)
printf("%d|", list[i]);
}
int main()
{
int i, low, high, n;
int *list;
printf("\nenter the no of elements:");
scanf("%d", &n);
list=(int *)malloc(sizeof(int) * n);
for(i = 0;i < n; i++)
scanf("%d", &list[i]);
low = 0;
high = n - 1;
mergesort(list, low, high);
printf("\nsorted list is:\n");
display(list, n);
return 0;
}
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