源代码如下

#include<bits/stdc++.h>
using namespace std;
inline int read()
{
	int w=1,s=0;char ch=getchar();
	while(!isdigit(ch)) {if(ch=='-')w=-1;ch=getchar();}
	while(isdigit(ch)){s=s*10+(ch-'0');ch=getchar();}
	return w*s;
}
int h,n;
struct no
{
	int y,nxt;
}edge[1000100];
int head[1000100],len;
void add(int x,int y)
{
    edge[++len]=(no){y,head[x]};
	head[x]=len;	
} 
struct dian
{
	int x,y;
}w[1000100];
double dis(dian a,dian b)
{
	return sqrt(1.0*(a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
int dist[1000100];
bool vis[1000100];
struct noo
{
	int v,id;
	inline friend operator <(noo qq,noo ww)
	{
	    return qq.v>ww.v;	
	} 
};
priority_queue<noo> q;
void work()
{
	memset(dist,0x3f,sizeof dist);
	dist[0]=0;
	q.push({0,0});
	while(q.size())
	{
		int x=q.top().id;
		q.pop();
		if(vis[x]) continue;
		vis[x]=1;
		for(int i=head[x];i;i=edge[i].nxt)
		{
			int y=edge[i].y;
			if(dist[y]>dist[x]+1)
			{
				dist[y]=dist[x]+1;
				q.push({dist[y],y});
			}
		}
	}
}
int main()
{
    cin>>h>>n;
    for(int i=1;i<=n;i++)
    {
    	w[i].x=read();w[i].y=read();
    	if(w[i].y<=1000) 
    	{
    		add(0,i);
		}
		if(h-w[i].y<1000) 
		{
			add(i,n+1);
		}
	}
	for(int i=1;i<n;i++)
	{
		for(int j=i+1;j<=n;j++)
		{
			if(dis(w[i],w[j])<=1000.0)
			{
				add(i,j);
				add(j,i);
			}
		}
	}
	work();
	cout<<dist[n+1]-1;
	return 0;
}

本地编译可以过，但是在洛谷上CE了，请问是为什么？