Submission #1628068

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Source Code Expand

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<set>
#include<bitset>
#include<map>

#define fo(i,a,b) for(int i=a;i<=b;i++)
#define fd(i,a,b) for(int i=a;i>=b;i--)

using namespace std;

typedef long long LL;
typedef double db;

int get(){
	char ch;
	while(ch=getchar(),(ch<'0'||ch>'9')&&ch!='-');
	if (ch=='-'){
		int s=0;
		while(ch=getchar(),ch>='0'&&ch<='9')s=s*10+ch-'0';
		return -s;
	}
	int s=ch-'0';
	while(ch=getchar(),ch>='0'&&ch<='9')s=s*10+ch-'0';
	return s;
}

const int H = 210;

int n,h;
int deg[H*2];
int cnt[H*2];
int fa[H*2];
bool bz[H*2];

int getfather(int x){
	if (fa[x]==x)return fa[x];
	return fa[x]=getfather(fa[x]);
}

int main(){
	fo(i,0,h*2)fa[i]=i;
	n=get();h=get();
	fo(i,1,n){
		int a=get(),b=get(),c=get(),d=get();
		if (c)a=-c;
		if (d)b=d;else b=-b;
		a+=h;b+=h;
		int ta=getfather(a),tb=getfather(b);
		deg[a]++;deg[b]--;
		fa[ta]=tb;
	}
	bool ans=1;
	fo(i,0,h-1)if (deg[i]>0)ans=0;
	fo(i,h+1,2*h)if (deg[i]<0)ans=0;
	if (ans){
		fo(i,0,2*h){
			int t=getfather(i);
			if (t!=i)bz[t]=1;
			if (deg[i]!=0)cnt[t]++;
		}
		fo(i,0,2*h)
		if (bz[i]&&!cnt[i])ans=0;
	}
	if (ans)printf("YES\n");
	else printf("NO\n");
	return 0;
}

Submission Info

Judge Result