【NOIP2017提高组 day2】奶酪

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题目

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题解

–很简单，就是n^2建图，bfs一遍就好了，记得开longlong

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代码

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
using namespace std;
const int MAXN=1005;

int t,n;
long long h,r;
long long x[MAXN],y[MAXN],z[MAXN];
vector<int>g[MAXN];
int q[MAXN],head,tail;
bool isv[MAXN];

long long f(long long a){
	return a*a;
}

long long l(int a,int b){
	return f(x[a]-x[b])+f(y[a]-y[b])+f(z[a]-z[b]);
}

bool bfs(){
	head=1;
	tail=1;
	q[head]=0;
	isv[0]=1;
	while(head<=tail){
		int x=q[head];
		if(x==n+1)
			return 1;
		for(int i=0;i<g[x].size();i++){
			int y=g[x][i];
			if(!isv[y]){
				q[++tail]=y;
				isv[y]=1;
			}
		}
		head++;
	}
	return 0;
}

int main(){
//	freopen("cheese.in","r",stdin);
//	freopen("cheese.out","w",stdout);
	cin>>t;
	while(t--){
		scanf("%d%lld%lld",&n,&h,&r);
		for(int i=0;i<=n+1;i++)
			g[i].clear();
		for(int i=1;i<=n;i++){
			scanf("%lld%lld%lld",&x[i],&y[i],&z[i]);
			for(int j=1;j<i;j++)
				if(l(i,j)<=4*r*r){
					g[i].push_back(j);
					g[j].push_back(i);
				}
			if(z[i]<=r){
				g[0].push_back(i);
				g[i].push_back(0);
			}
			if(z[i]+r>=h){
				g[n+1].push_back(i);
				g[i].push_back(n+1);
			}
		}
		memset(isv,0,sizeof(isv));
		if(bfs())
			printf("Yes\n");
		else
			printf("No\n");
	}
	return 0;
}