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# merge sort in c

Merge Sort is a Divide and Conquer algorithm. It divides input array in two halves, calls itself for the two halves and then merges the two sorted halves. The merg() function is used for merging two halves. The merge(arr, l, m, r) is key process that assumes that arr[l..m] and arr[m+1..r] are sorted and merges the two sorted sub-arrays into one. See following C implementation for details.

PROGRAM:

/* c program for merge sorting */

#include<stdio.h>
#include<conio.h>
void merge(int [],int ,int ,int );
void part(int [],int ,int );
int main()
{
int arr[30];
int i,size;
printf(“\n\t——- Merge sorting method ——-\n\n”);
printf(“Enter total no. of elements : “);
scanf(“%d”,&size);
for(i=0; i<size; i++)
{
printf(“Enter %d element : “,i+1);
scanf(“%d”,&arr[i]);
}
part(arr,0,size-1);
printf(“\n\t——- Merge sorted elements ——-\n\n”);
for(i=0; i<size; i++)
printf(“%d “,arr[i]);
getch();
return 0;
}

void part(int arr[],int min,int max)
{
int mid;
if(min<max)
{
mid=(min+max)/2;
part(arr,min,mid);
part(arr,mid+1,max);
merge(arr,min,mid,max);
}
}

void merge(int arr[],int min,int mid,int max)
{
int tmp[30];
int i,j,k,m;
j=min;
m=mid+1;
for(i=min; j<=mid && m<=max ; i++)
{
if(arr[j]<=arr[m])
{
tmp[i]=arr[j];
j++;
}
else
{
tmp[i]=arr[m];
m++;
}
}
if(j>mid)
{
for(k=m; k<=max; k++)
{
tmp[i]=arr[k];
i++;
}
}
else
{
for(k=j; k<=mid; k++)
{
tmp[i]=arr[k];
i++;
}
}
for(k=min; k<=max; k++)
arr[k]=tmp[k];
}

OUTPUT: