Shortest seek time first (SSTF)

from 100 Track number begins
Next track accessed	Moving distance （ Track number ）
90	10
58	32
55	3
39	16
38	1
18	20
150	132
160	10
184	24
Average seek length ：27.5

#include<iostream>
#include<algorithm>
#include<list>
#include <fstream>
#include<iterator>
#include<vector>
#include <functional>
#include<cmath>
using namespace std;

class SSTF
{
public:
	int id;// Number 
	int dis;// distance 
	SSTF()
	{
		dis = 0;

	}
	friend ostream & operator <<(ostream &o, const  SSTF &s);
	friend istream & operator >>(istream &i ,SSTF &s);
	bool operator ==(const SSTF &s)
	{
		if (s.id==this->id)
		{
			return true;
		}
		return false;
	}
	bool operator>(const SSTF &s)
	{
		if (this->id>s.id )
		{
			return true;
		}
		return false;
	}
	bool operator<(const SSTF &s)
	{
		if (this->id < s.id)
		{
			return true;
		}
		return false;
	}
	SSTF & operator=(const SSTF &s)
	{
		this->id = s.id;
		this->dis = s.dis;
		return *this;
	}
};
ostream & operator <<(ostream &o, const  SSTF &s)
{
	o << s.id << "\t" << s.dis;
	return o;
}
istream & operator >>(istream &i, SSTF &s)
{
	i >> s.id ;
	return i;
}
void main()
{
	fstream out("data.txt");
	list<SSTF>v;
	copy(istream_iterator<SSTF>(out),istream_iterator<SSTF>(),back_inserter(v));
	copy(v.begin(), v.end(), ostream_iterator<SSTF>(cout));
	float num=0.0;
	int begin = 100;
	v.sort();
	cout << "\n The result is :" << endl;
	cout << " The order of access is :" << endl;
	while (v.size()!=0)
	{
		transform(v.begin(), v.end(), v.begin(), [begin](SSTF &s)->SSTF {s.dis = abs(begin - s.id);return s; });
		list<SSTF>::iterator min = min_element(v.begin(), v.end(), [](const SSTF &s1,const SSTF &s2)->bool {return s1.dis > s2.dis ? false : true; });
		begin = min->id;
		cout << *min << endl;
		num += min->dis;
		v.remove(*min);
	}
	cout <<" Average seek time :"<< (num / 9) << endl;

	cin.get();
}

data.txt

test result :