Bresenham's Line Drawing Algorithm

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

#define fastread() (ios_base:: sync_with_stdio(false),cin.tie(NULL));


int main()
{

   fastread();

   ll i,j,n,m,p,a,sum=0,k,t,b,c,d,cnt=0,q,l,r,ans=0;

      bool flag=false;

      string str;

      ll x1,x2,y1,y2;

      cin>>x1>>y1>>x2>>y2;

      ll delx= abs(x2-x1);

      ll dely = abs(y2-y1);



      ll Twodely = dely*2;

      ll TwoDelyMinus2delx = Twodely - (2*delx);

        p = Twodely - delx;

        ll preP=p;

        cout<<endl;

        cout<<"K Pk (Xk+1 , Yk+1)"<<endl;

        cout<<endl<<endl;

      for(ll k=0; k<delx; k++)
      {
          if(p<0)
          {
              p = p+Twodely;
              x1++;



          }
          else{

            p= p+TwoDelyMinus2delx;

             x1++;
             y1++;
          }

          cout<<k<<" "<<preP<<"  ("<<x1<<" "<<y1<<")"<<endl;

          preP=p;
      }







      return 0;


}