HDU4183_Pahom on Water

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <queue>
#include <vector>
#define maxn 333
using namespace std;

vector<int> v[maxn];
int c[maxn][maxn],pre[maxn],tag[maxn];
bool can[maxn];
int n,m,s,t,T,ans,N=1;
double hz[maxn];
int x[maxn],y[maxn],r[maxn];
int Q[maxn],bot,top;

int dis(int x1,int y1,int x2,int y2)
{
	return (x2-x1)*(x2-x1)+(y2-y1)*(y2-y1);
}

void _init()
{
	ans=0;
	for (int i=1; i<=n; i++)
	{
		v[i].clear();
		for (int j=1; j<=n; j++) c[i][j]=0;
	}
	for (int i=1; i<=n; i++)
	{
		scanf("%lf%d%d%d",&hz[i],&x[i],&y[i],&r[i]);
		if (hz[i]==400) s=i;
		if (hz[i]==789) t=i;
	}
}

void graph_build()
{
	for (int i=1; i<=n; i++)
		for (int j=1; j<=n; j++)
		{
			if (hz[j]<=hz[i]) continue;
			if (dis(x[i],y[i],x[j],y[j])<(r[i]+r[j])*(r[i]+r[j]))
				c[i][j]=1,v[i].push_back(j),v[j].push_back(i);
		}
}

bool EK(int TAG)
{
	Q[bot=top=1]=s,tag[s]=TAG;
	while (bot<=top)
	{
		int cur=Q[bot++];
		for (unsigned i=0; i<v[cur].size(); i++)
			if (tag[v[cur][i]]!=TAG && c[cur][v[cur][i]]>0)
			{
				tag[v[cur][i]]=TAG;
				Q[++top]=v[cur][i];
				pre[v[cur][i]]=cur;
				if (v[cur][i]==t)
				{
					for (int k=t; k!=s; k=pre[k]) c[pre[k]][k]=0,c[k][pre[k]]=1;
					return true;
				}
			}
	}
	return false;
}


int main()
{
	scanf("%d",&T);
	while (T--)
	{
		scanf("%d",&n);
		_init(); 
		graph_build();
		if (c[s][t])
		{
			puts("Game is VALID");
			continue;
		}
		ans=1;
		for (int i=1; i<=2; i++) 
			if (!EK(++N)) 
			{
				ans=0;
				break;
			}
		if (ans) puts("Game is VALID");
			else puts("Game is NOT VALID");
	}
	return 0;
}