#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<fstream.h>
#include<iostream.h>
#include<stdlib.h>
class record
{
        public:
        char name[20];
        char usn[20];
}rec[20];
fstream file[8];
int no;
char fname[8][8]={"z1.txt","z2.txt","z3.txt","z4.txt","z5.txt","z6.txt","z7.txt","z8.txt"};
void merge_file(char*file1,char*file2,char*filename)
{
        record recd[20];
        int i,k;
        k=0;
        fstream f1,f2;
        f1.open(file1,ios::in);
        f2.open(file2,ios::in);
        while(!f1.eof())
        {
                f1.getline(recd[k].name,20,'|');
                f1.getline(recd[k++].usn,20,'\n');
        }
        while(!f2.eof())
        {
                f2.getline(recd[k].name,20,'|');
                f2.getline(recd[k++].usn,20,'\n');
        }
        int t,y;
        record temp;
        for(t=0;t<k-2;t++)
        for(y=0;y<k-t-2;y++)
        if(strcmp(recd[y].name,recd[y+1].name)>0)
        {
                temp=recd[y];
                recd[y]=recd[y+1];
                recd[y+1]=temp;
        }
        fstream temp1;
        temp1.open(filename,ios::out);
        for(t=1;t<k-1;t++)
        temp1<<recd[t].name<<"|"<<recd[t].usn<<"\n";
        f1.close();
        f2.close();
        temp1.close();
        return;
}
void kwaymerge()
{
        int i,k;
        k=0;
char      filename[7][20]={"z11.txt","z22.txt","z33.txt","z44.txt","z111.txt","z222.txt","z1111.txt"};
        for(i=0;i<8;i+=2)
        {
                merge_file(fname[i],fname[i+1],filename[k++]);
        }
       k=4;
        for(i=0;i<4;i+=2)
        {
                merge_file(filename[i],filename[i+1],filename[k++]);
        }
                merge_file(filename[4],filename[5],filename[6]);return;
        }
        void main()
        {
                int i;
                clrscr();
                cout<<"enter no of records\n";
                cin>>no;
                cout<<"\n enter the details\n";
                for(i=0;i<8;i++)
                file[i].open(fname[i],ios::out);
                for(i=0;i<no;i++)
                {
                        cout<<"Name:";

                        cin>>rec[i].name;
                        cout<<"Usn:";
                        cin>>rec[i].usn;
                        file[i%8]<<rec[i].name<<"|"<<rec[i].usn<<"\n";
                }
                for(i=0;i<8;i++)
                file[i].close();
                kwaymerge();
                fstream result;
                result.open("z1111.txt",ios::in);
                cout<<"sorted records\n";
                char name[20],usn[20];
                for(i=0;i<no;i++)
                {
                        result.getline(name,20,'|');
                        result.getline(usn,20,'\n');
                        cout<<"\nName:"<<name<<"\nUsn:"<<usn<<"\n";
                }
                getch();
}