C++ program to implement Merge Sort

/*-------------------------------------------------------------------------------------------------------------

File Name:      merge.cpp

Author:           sujith

Program:        Write a C++ program to implement Merge Sort

Date:               21-04-2015

--------------------------------------------------------------------------------------------------------------*/

#include<iostream>

#include<stdio.h>

using namespace std;

void mergesort(int a[20],int n);

int main()

{

        int i,n,a[20];

        cout<<"Enter the total number of element\n";

        cin>>n;

        cout<<"Enter the Elements\n";

        for(i=0;i<n;i++)

        {

                cin>>a[i];

        }

        cout<<"After sorting\n";

        mergesort(a,n);

        for(i=0;i<n;i++){

        cout<<a[i]<<"\n";

        }

}

void mergesort(int a[20],int n)

{

        int aux[20],i,j,k,l1,l2,u1,u2,size;

        size=1;

        while(size<n)

        {

        l1=0;

        k=0;

        while(l1+size<n)

        {

                l2=l1+size;

                u1=l2-1;

                u2=(l2+size-1<n)?l2+size-1:n-1;

        for(i=l1,j=l2;i<=u1&&j<=u2;k++)

        {

                if(a[i]<=a[j]){

                        aux[k]=a[i++];

                }else{

                        aux[k]=a[j++];

                }

        }

        for(;i<=u1;k++){

                aux[k]=a[i++];

        }

        for(;j<=u2;k++){

                aux[k]=a[j++];

        }

                l1=u2+1;

        }

        for(i=l1;i<n;i++)

                aux[k++]=a[i];

        for(i=0;i<n;i++)

                a[i]=aux[i];

                size=size*2;

        }

}

OUTPUT:

[141740@localhost ~]$ g++ merge.cpp

[141740@localhost ~]$ ./a.out

Enter the total number of element

5

Enter the Elements

11        33        55        22        88

After sorting

11

22

33

55

88