Merge sort is a sorting algorithm that uses the divide, conquer and combine algorithm paradigm.

A] Divide: It means partitioning the n-element array to be sorted into two sub arrays of n/2 elements in each sub-array.

B] conquer: It means sorting the two arrays recursively using merge sort.

C] combine: It means merging two sorted sub array of size n/2 each to produce the sorted array of n elements.

Program:

include < stdio.h>

include <conio.h>

vid merge (int a [ ] , int, int, int);

void merge sort (int a [ ] , int , int ) ;

void main ( )

<

int a [10] , i, n, j , k;

print t ("in enter no of elements in array = ");

scan f ("%d",&n);

print f ("in enter elements of array ");

for (i=0; i<n; itt)</p>

<

print f ("in a [% d] = " ! i);

scan f (" % d " , & a [i]);

3

merge sort (a, o , n-1);

print t ("in sorted array = in ");

for (i = 0 ; i < n; itt)

<

print f ("+%d",a[i]);

3

getch ( ) ;

3

void merge (int a [ ] , int beg, int mid, int end)

<

int i = beg, j = mid + 1 , index = beg, temp [10], k; while (c i < 0 mid) & & (j <0 end) )

<

if (a [i] < a [j])

<

temp [index] = a [i];

itt;

3

else

temy [index] = a [j[;

jtt;

3

index tt ;

<

if (i > mid)

<

while (j <0 end)

<

temp [index] = a [j] ;

jtt;

index tt;

3

3 else

<

while (i < = mid)

<

temp [index] = a [i];

itt;

index tt;

3 3 for (k = beg i k < index ; ktt)

< a[k] = temp [k];

3

3

void merge sort (int a [ ] , int beg, int end)

<

int mid;

if (beg < end)

<

mid = (beg + end) / 2 ;

merge-sort (a, beg, mid);

merge - sort (a, mid + 1 , end);

merge (a , beg , mid , end);

3

3