poj2007 叉乘排序

#include <iostream>
#include <cstdio>
#include <iomanip>
#include <string>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <set>
#include <vector>
#include <map>
#include <algorithm>
#include <cmath>
#include <stack>

#define INF 0x3f3f3f3f
#define LINF 0x3f3f3f3f3f3f3f3f
#define ll long long
#define ull unsigned long long
#define uint unsigned int

using namespace std;

struct Point {
	int x, y;
	Point():x(0),y(0){}
	Point(int a,int b) :x(a),y(b){}
	Point operator-(const Point &b) {
		return Point(x - b.x, y - b.y);
	}

}a[55],o;

int cross(Point a, Point b) {
	a = a - o;
	b = b - o;
	return a.x*b.y - b.x*a.y;
}

bool operator<(const Point &a,const Point &b) {
	return cross(a, b) > 0;
}

int main(){
	int n = 0;
	while (~scanf("%d%d", &a[n].x, &a[n].y))n++;

	o = a[0];
	sort(a + 1, a + n);
	for (int i = 0; i < n; i++)
		printf("(%d,%d)\n", a[i].x, a[i].y);
	
	return 0;
}