CPP Program to implement merge sort

Source Code :

#include<iostream>

using namespace std;

void swapping(int &a,int &b)

{

int temp;

temp = a;

a = b;

b = temp;

}

void display(int *array, int size)

{

for(int i = 0;i<size;i++)

   cout<<array[i]<<" ";

    cout<<endl;

}

void merge(int *array, int l, int m, int r )

{

int i,j,k,nl,nr;

nl = m-l+1; nr = r-m;

int larr[nl], rarr[nr];

for(i=0;i<nl;i++)

  larr[i] = array[l+i];

for(j=0;j<nr;j++)

   rarr[j] = array[m+1+j];

i=0; j=0; k=l;

while(i < nl && j<nr)

{

if(larr[i] <= rarr[j])

{

array[k] = larr[i];

i++;

}

else

{

array[k] = rarr[j];

j++;

}

k++;

} 

while(i<nl) 

{

array[k] = larr[i];

i++; k++;

}

while(j<nr)

{

array[k] = rarr[j];

j++; k++;

}

}

void mergeSort(int *array,int l,int r)

{

int m;

if(l < r)

{

int m = l+(r-1)/2;

mergeSort(array,l,m);

mergeSort(array,m+1,r);

merge(array,l,m,r);

}

}

int main()

{

int n;

cout<< "Enter the number of elements: ";

cin>>n;

int arr[n];

cout<<"Enter elements: "<<endl;

{

for(int i = 0; i<n; i++)

{

cin>>arr[i];

}

}

cout<<"Array before Sorting: ";

display(arr , n);

mergeSort(arr, 0, n-1);

cout<<"Array after Sorting: ";

display(arr , n);

return 0;

}

Program Output :