Can you help me? The problem "Triangle Classification"

general
1

my problem’s link
my code:

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <stdio.h>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <iomanip>
#include <list>
#include <deque>
#include <stack>
#define ull unsigned long long
#define ll long long 
#define cle(a) memset(a,0,sizeof(a))
const double eps=1e-6;
using namespace std;
struct node{
    int x,y;
}nod[4]; 
bool cmp(int a,int b){ 
    return a>b; 
} 
int dis(node a,node b){ 
return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y); 
} 
int main() 
{  
    #ifndef ONLINE_JUDGE 
    freopen("in.txt","r",stdin); 
    #endif 
    //freopen("out.txt","w",stdout); 
int t,n,mark; 
    cin>>t;  
	cin>>n; 
	    for(int i=1;i<=n;i++){ 
		    cin>>nod[1].x>>nod[1].y>>nod[2].x>>nod[2].y>>nod[3].x>>nod[3].y; 
		    int A[3]; 
		    A[0]=dis(nod[1],nod[2]); 
		    A[1]=dis(nod[3],nod[2]); 
		    A[2]=dis(nod[1],nod[3]); 
		    sort(A,A+3); 
		    mark=0; 
		    if(A[0]==A[1]||A[1]==A[2])mark=1; 
		    if(t==1){ 
			    if(mark)cout<<"Isosceles triangle"<<endl; 
			    else cout<<"Scalene triangle"<<endl; 
			    continue; 
		    } 
		    if(A[2]>A[1]+A[0]){ 
			    if(!mark)cout<<"Scalene obtuse triangle"<<endl; 
			    else cout<<"Isosceles obtuse triangle"<<endl; 
		    } 
		    else if(A[2]==A[1]+A[0]){ 
			    if(mark)cout<<"Isosceles right triangle"<<endl; 
			    else cout<<"Scalene right triangl"<<endl; 
		    } 
		    else { 
			    if(mark)cout<<"Isosceles acute triangle"<<endl; 
			    else cout<<"Scalene acute triangle"<<endl; 
		    } 
	    } 
    return 0; 
}

I really can not find where is wrong？

2
  1. Define everything as double when dealing with pts / distances 2.Dont use == to compare floating pt values.Read the problem statement.It is given at the end as a note. 3.Your formula to determine angle is wrong.Sum of any 2 sides of a triangle will always be greater than the third. Use cosine formula to find angle.
3

I tried to remove this: #ifndef ONLINE_JUDGE
freopen(“in.txt”,“r”,stdin);
#endif
and it worked just fine

4

and about the:

Your formula to determine angle is wrong.Sum of any 2 sides of a triangle will always be greater than the third. Use cosine formula to find angle.

he isn’t doing a sum of 2 sides, he is doing a sum of 2 squares at these sides and from that, acording to pythagoras theorem, he is able to determine whether the triangle is right, acute, or obtuse and I think this method is quicker than cosine