Coding Solutions Group

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

#define pdd pair<double, double>
void lineFromPoints(pdd P, pdd Q){
  double a = Q.second - P.second;
  double b = P.first - Q.first;
  double c = a * (P.first) + b * (P.second);
  if (b < 0) 
    cout<< a << "x " << b << "y = " << c << endl;
  else 
    cout<< a << "x + " << b << "y = " << c << endl;
  
}
int collinear(int x1, int y1, int x2, int y2, int x3, int y3){
  if ((y3 - y2) * (x2 - x1) == (y2 - y1) * (x3 - x2))
    return 1;
  else
    return 0;
}

int main(){
  int x1 = 1, x2 = 1, x3 = 0,
    y1 = 1, y2 = 6, y3 = 9;
  int n;
  cin>>n;
  int x[n],y[n];
  for(int i=0;i<n;i++) cin>>x[i]>>y[i];
  pdd p1 = {x[0],y[0]}, q1 = {x[1], y[1]};
  if(n == 2) lineFromPoints(p1, q1);
  else{
    int flag = 1;
    for(int i=2;i<n;i++)
      if(collinear(x[i-2], y[i-2], x[i-1], y[i-1], x[i], y[i]) != 1){
        flag = 0;
        break;
      }
    if(flag) lineFromPoints(p1, q1);
    else cout<<flag;
  }
  
  return 0;
}