题解

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=1005;
bool f[N][N],vis[N];
int T,n;
ll x[N],y[N],z[N],h,r;
ll sqr(ll x){
    return x*x;
}
int main(){
    cin>>T;
    while(T--){
        cin>>n>>h>>r;
        memset(f,0,sizeof(f));
        memset(vis,0,sizeof(vis));
        for(int i=1;i<=n;i++) cin>>x[i]>>y[i]>>z[i];
        for(int i=1;i<=n;i++){
            if(z[i]<=r) f[0][i]=f[i][0]=1;
            if(z[i]>=h-r) f[n+1][i]=f[i][n+1]=1;
        }
        for(int i=1;i<=n;i++){
            for(int j=i+1;j<=n;j++){
                if(sqr(x[i]-x[j])+sqr(y[i]-y[j])+sqr(z[i]-z[j])<=r*r*4){
                    f[i][j]=f[j][i]=1;
                }
            }
        }
        queue<int> q;
        q.push(0);
        vis[0]=1;
        while(!q.empty()){
            int u=q.front();
            q.pop();
            for(int i=1;i<=n+1;i++){
                if(f[u][i]&&!vis[i]){
                    q.push(i);
                    vis[i]=1;
                }
            }
        }
        if(vis[n+1]) cout<<"Yes"<<endl;
        else cout<<"No"<<endl;
    }
}