1 /*
2 几何+凸包逆序输出+极角排序
3 */
4 #include<stdio.h>
5 #include<string.h>
6 #include<stdlib.h>
7 #include<math.h>
8 #include<algorithm>
9 using namespace std;
10 const int maxn = 55;
11 const double eps = 1e-8;
12 struct Point{
13 double x,y;
14 };
15 Point point[ maxn ];
16
17 double xmult( Point sp,Point ep,Point op ){
18 return ( sp.x-op.x )*( ep.y-op.y )-( sp.y-op.y )*( ep.x-op.x );
19 }
20
21 int sig( double d ){
22 if( d>eps ) return 1;
23 if( d<-eps ) return -1;
24 return 0;
25 }
26
27 double dist( Point a,Point b ){
28 double sum = ( a.x-b.x )*( a.x-b.x )+( a.y-b.y )*( a.y-b.y );
29 return sqrt( sum );
30 }
31
32 int cmp( Point a, Point b ){
33 return sig( xmult(a,b,point[0]) )>0;
34 }
35
36 int main(){
37 int n = 0;
38 while( scanf("%lf%lf",&point[ n ].x,&point[ n ].y )!=EOF )
39 n++;
40 sort( point+1,point+n,cmp );
41 for( int i=0;i<n;i++ ){
42 printf("(%.0lf,%.0lf)\n",point[ i ].x,point[ i ].y);
43 }
44 return 0;
45 }
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