Scrambled Polygon POJ - 2007(极角排序）
Scrambled Polygon
题意：
思路：其实就是将（0，0）这个点按照极角排序，其他点对于（0，0）来排序，将排序后输出就行，注意输入不定
1 // 2 // Created by HJYL on 2020/1/17. 3 // 4 #include<iostream> 5 #include<cstring> 6 #include<cstdio> 7 #include<cmath> 8 #include<algorithm> 9 using namespace std; 10 const double eps=1e8; 11 int dcmp(double x) 12 { 13 if(fabs(x)<eps) 14 return 0; 15 return x<0?-1:1; 16 } 17 struct Point{ 18 int x,y; 19 int id; 20 Point(){} 21 Point(int id,double x,double y):id(id),x(x),y(y){} 22 }initial;//以当前点来求最外凸包 23 24 typedef Point Vector; 25 26 Vector operator-(Point A,Point B) 27 { 28 return Vector(-1,A.x-B.x,A.y-B.y); 29 } 30 //叉积 31 double Cross(Vector A,Vector B) 32 { 33 return A.x*B.y-A.y*B.x; 34 } 35 36 double Len(Point A,Point B) 37 { 38 return (A.x-B.x)*(A.x-B.x)+(A.y-B.y)*(A.y-B.y); 39 } 40 41 //极角排序 42 bool cmp(const Point& A,const Point& B) 43 { 44 double t=Cross(A-initial,B-initial); 45 if(t>0)//叉积大于0，B在A的左边，A在外凸包上 46 return true; 47 else if(t<0) 48 return false; 49 else 50 return Len(A,initial)<Len(B,initial);//极角相同采用最近的点 51 52 } 53 54 const int maxn=100; 55 int main() 56 { 57 Point p[maxn]; 58 int x,y; 59 while(~scanf("%d%d",&x,&y)) 60 { 61 int num=0; 62 initial=Point(0,0,0); 63 while(~scanf("%d%d",&p[num].x,&p[num].y)){ 64 num++; 65 } 66 printf("(0,0)\n"); 67 for(int i=0;i<num;i++) 68 { 69 sort(p,p+num,cmp); 70 printf("(%d,%d)\n",p[i].x,p[i].y); 71 } 72 } 73 return 0; 74 }
