直接贪心，每次找距离当前点最近的点，期望能拿多少分？

#include<bits/stdc++.h>
#define N 1010
using namespace std;
const double INF=999999999;
int n,vis[N],k,_max=-114514;
double x[N],y[N],s[N][N];
double check(double a,double b,double c, double d){
	double ans;
	ans=sqrt((a-c)*(a-c)+(b-d)*(b-d));
	return ans;
}
void dfs(int p){
	cout << p << " ";
	vis[p]=1;
	double _min=INF;
	int h=-1;
	for(int i=1;i<=n;i++){
		if(s[p][i]<_min&&vis[i]==0){
			_min = s[p][i];
			h = i;
		}
	} 
	if(h!=-1) dfs(h);
}
int main(){
	//freopen("tree.in","r",stdin);
	//freopen("tree.out","w",stdout);
	cin >> n;
	for(int i=1;i<=n;i++){
		cin >> x[i] >> y[i];
		if(y[i]>_max){
			_max=y[i];
			k=i;
		}
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			if(i==j){
				s[i][j]=INF;
				s[j][i]=INF;
			}
			else{
				s[i][j] = check(x[i],y[i],x[j],y[j]);
				s[j][i] = s[i][j];
			}
		}
	}
	vis[k]=1;
	dfs(k);
	return 0;
}