poj1969

Source Code

Problem: 1696		User: Praesidio
Memory: 188K		Time: 0MS
Language: C++		Result: Accepted

• Source Code

  //poj1696
  #include <iostream>
  #include <cstdio>
  #include <cmath>
  #include <cstring>
  #include <algorithm>
  using namespace std;
  #define sqr(x) ((x)*(x))
  const double eps = 1e-9;
  const double pi = acos(-1.0);
  int sgn (const double &x) { return (x>eps) - (x< -eps); }
  struct Point {
  	int id;
  	double x,y;
  	Point () {	}
  	Point (double x,double y) : x(x),y(y) {	} 
  };
  typedef Point Vector;
  Vector operator - (Point A,Point B) {return Vector(A.x-B.x,A.y-B.y); }
  double operator ^ (Vector A,Vector B) {return A.x*B.x+A.y*B.y; }
  double operator * (Vector A,Vector B) {return A.x*B.y-A.y*B.x; }
  bool operator == (Point A,Point B) {
  	return sgn(A.x-B.x)==0 && sgn(A.y-B.y)==0 ; 
  }
  
  struct Line {
  	Point p;
  	Point q;
  	Vector v;
  	double ang;
  	double ang2;
  	Line () {}
  	Line (Point p,Point q) : p(p),q(q) {
  		v = q-p;
  		ang = atan2 (v.y , v.x);
  		if (sgn(ang)==-1) ang += 2*pi;	
  	}
  	bool operator < (const Line& L) const {
  		return ang<L.ang;
  	} 
  };
  
  int n;
  Point point[55];
  Line line[55];
  int vis[55];
  
  void init()
  {
  	scanf("%d",&n);
  	for (int i=0;i<n;i++) {
  		scanf("%d%lf%lf",&point[i].id,&point[i].x,&point[i].y);
  	}
  }
  bool cmp(Point A,Point B) {
  	return (A.y != B.y)? A.y<B.y : A.x<B.x ;
  }
  int main()
  {
  	int test;
  	scanf("%d",&test);
  	while (test--) {
  		init();
  		sort (point,point+n,cmp);
  		printf("%d ",n);
  		Point pole = point[0];
  		memset(vis,0,sizeof(vis));
  		int tmp=n-1;
  		double angle=0;
  		printf("%d",pole.id);
  		while (tmp--) {
  
  			vis[pole.id]=1;
  			int top=0;
  			
  			for (int i=0;i<n;i++) {
  				if (vis[point[i].id]) continue;
  				line[top] = Line ( pole , point[i] );
  				line[top].ang2 = line[top].ang;
  				line[top].ang -= angle;
  				if (sgn(line[top].ang)==-1) line[top].ang += 2*pi;
  				top++;
  			}
  						
  			sort(line,line+top);
  
  			pole = line[0].q;
  			angle= line[0].ang2 ;
  			
  			printf(" %d",pole.id);
  		}
  		printf("\n");
  	}
  	return 0;
  }