/*
Summary: Merge sort is a divide and conquer
comparison-based sorting algorithm. It works as follows:-
1. Divide the unsorted list into n sublists,
each containing 1 element (a list of 1 element is considered sorted).
2. Repeatedly merge sublists to produce new
sublists until there is only 1 sublist remaining.
This will be the sorted list.
Complexity - O(n·log n)
*/
#include <stdio.h>
void mergeSort(int [], int, int, int);
void partition(int [],int, int);
int main()
{
int list[50];
int i, size;
clrscr();
printf("Enter total number of elements:");
scanf("%d", &size);
printf("Enter the elements:\n");
for(i = 0; i < size; i++)
{
scanf("%d", &list[i]);
}
partition(list, 0, size - 1);
printf("After merge sort:\n");
for(i = 0;i < size; i++)
{
printf("%d ",list[i]);
}
getch();
return 0;
}
void partition(int list[],int low,int high)
{
int mid;
if(low < high)
{
mid = (low + high) / 2;
partition(list, low, mid);
partition(list, mid + 1, high);
mergeSort(list, low, mid, high);
}
}
void mergeSort(int list[],int low,int mid,int high)
{
int i, mi, k, lo, temp[50];
lo = low;
i = low;
mi = mid + 1;
while ((lo <= mid) && (mi <= high))
{
if (list[lo] <= list[mi])
{
temp[i] = list[lo];
lo++;
}
else
{
temp[i] = list[mi];
mi++;
}
i++;
}
if (lo > mid)
{
for (k = mi; k <= high; k++)
{
temp[i] = list[k];
i++;
}
}
else
{
for (k = lo; k <= mid; k++)
{
temp[i] = list[k];
i++;
}
}
for (k = low; k <= high; k++)
{
list[k] = temp[k];
}
}
