C++ STL 标准结构体排序

#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;

struct Point{
int x;
int y;
};
struct Rule1
{
bool operator()(const int &x,const int &y)
{
if(x%10<y%10)
{
return true;
}
else if(x%10>y%10)
{
return false;
}
else
{
if(x>y)
{
return true;
}
else
{
return false;
}
}
}
};
struct Rule2
{

bool operator()(const Point & A,const Point & B)
{
if(A.x*A.x+A.y*A.y<B.x*B.x+B.y*B.y)
{
return true;
}
else if(A.x*A.x+A.y*A.y>B.x*B.x+B.y*B.y)
{
return false;
}
else 
{
if(A.x<B.x)
{
return true;
}
else if(A.x>B.x)
{
return false;
}
else
{
if(A.y<B.y)
{
return true;
}
else
{
return false;
}
}
}
}
}; 
int main()
{
int a[8] = {6,5,55,23,3,9,87,10 };
sort(a,a+8,Rule1());
for(int i = 0;i < 8; ++i)
cout << a[i] << "," ; 
cout << endl;
Point ps[8] = {{1,0},{0,1},{0,-1},{-1,0},{1,-1},{1,1},{2,0},{-2,0} } ;
sort(ps,ps+8,Rule2());
for(int i = 0;i < 8; ++i)
cout << "(" << ps[i].x << "," << ps[i].y << ")"; 
return 0;
}