[CLYZ2017]day13

组织

solution

20分

缩环,暴力判\(DAG\)中的点两两之间连通性.

#include<cmath>
#include<ctime>
#include<queue>
#include<stack>
#include<cstdio>
#include<vector>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define M 105
#define N 100005
using namespace std;
typedef long long ll;
struct graph{
	int nxt,to;
}e[N];
int g[N],f[N],l[N],r[N],s[N],to[M],dfn[N],low[N],n,m,t,top,cnt;
bool a[M][M],ins[N];
queue<int> q;
inline int read(){
	int ret=0;char c=getchar();
	while(!isdigit(c))
		c=getchar();
	while(isdigit(c)){
		ret=(ret<<1)+(ret<<3)+c-'0';
		c=getchar();
	}
	return ret;
}
inline void addedge(int x,int y){
//	printf("%d %d\n",x,y);
	e[++cnt].nxt=g[x];g[x]=cnt;e[cnt].to=y;
}
inline void tarjan(int u){
	dfn[u]=low[u]=++cnt;
	s[++top]=u;ins[u]=true;
	for(int i=g[u];i;i=e[i].nxt)
		if(!dfn[e[i].to]){
			tarjan(e[i].to);
			low[u]=min(low[u],low[e[i].to]); 
		}
		else if(ins[e[i].to])
			low[u]=min(low[u],low[e[i].to]); 
	if(dfn[u]==low[u])
		while(s[top+1]!=u){
			f[s[top]]=u;
			ins[s[top--]]=false; 
		}
}
inline void bfs(){
	int u;cnt=0;
	for(int i=1;i<=n;++i)
		if(!to[i]) q.push(i);
	while(!q.empty()){
		s[++cnt]=u=q.front();q.pop();
		for(int i=g[u];i;i=e[i].nxt)
			if(!(--to[e[i].to]))
				q.push(e[i].to);
	}
	for(u=s[cnt--];cnt>=0;u=s[cnt--])
		for(int i=g[u];i;i=e[i].nxt){
			a[u][e[i].to]=true;
			for(int j=1;j<=n;++j)
				a[u][j]|=a[e[i].to][j];
		}
}
inline void Aireen(){
	scanf("%d",&n);
	scanf("%d",&m);
	for(int i=1;i<=m;++i){
		scanf("%d%d",&l[i],&r[i]);
		addedge(l[i],r[i]);
	}
	cnt=0;
	for(int i=1;i<=n;++i)
		if(!dfn[i]) tarjan(i);
	if(n<=100){
		cnt=0;
		memset(g,0,sizeof(g));
		for(int i=1;i<=m;++i)
			if(f[l[i]]!=f[r[i]]){
				addedge(f[l[i]],f[r[i]]);++to[r[i]];
			}
		bfs(); 
		scanf("%d",&t);
		for(int i=1,j,k;i<=t;++i){
			scanf("%d%d",&j,&k);
			if(f[j]==f[k]||a[f[j]][f[k]]){
				puts("NO");return;
			}
		}
		puts("YES"); 
		printf("%d\n",m);
		for(int i=1;i<=m;++i)
			printf("%d %d\n",l[i],r[i]);
		return;
	}
	scanf("%d",&t);
	for(int i=1,j,k;i<=t;++i){
		scanf("%d%d",&j,&k);
		if(f[j]!=f[k]){
			puts("NO");return;
		}
	}
	puts("YES"); 
	printf("%d\n",m);
	for(int i=1;i<=m;++i)
		printf("%d %d\n",l[i],r[i]);
}
int main(){
	freopen("gplt.in","r",stdin);
	freopen("gplt.out","w",stdout);
	Aireen();
	fclose(stdin);
	fclose(stdout);
	return 0;
}

100分

缩环,分块,用\(bitset\)求出所有点到这一块的点的连通性,判是否可行.

#include<cmath>
#include<ctime>
#include<queue>
#include<stack>
#include<cstdio>
#include<bitset>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define M 10000
#define N 100005
#define min(a,b) a<b?a:b
using namespace std;
typedef long long ll;
struct graph{
	int nxt,to;
}e[N];
int g[N],l[N],r[N],x[N],y[N],n,m,k,cnt;
bitset<M+10> a[N];
inline int read(){
	int ret=0;char c=getchar();
	while(!isdigit(c))
		c=getchar();
	while(isdigit(c)){
		ret=(ret<<1)+(ret<<3)+c-'0';
		c=getchar();
	}
	return ret;
}
inline void addedge(int x,int y){
	e[++cnt].nxt=g[x];g[x]=cnt;e[cnt].to=y;
}
int f[N],s[N],dfn[N],low[N],top;bool ins[N];
inline void tarjan(int u){
	dfn[u]=low[u]=++cnt;
	s[++top]=u;ins[u]=true;
	for(int i=g[u];i;i=e[i].nxt)
		if(!dfn[e[i].to]){
			tarjan(e[i].to);
			low[u]=min(low[u],low[e[i].to]); 
		}
		else if(ins[e[i].to])
			low[u]=min(low[u],low[e[i].to]); 
	if(dfn[u]==low[u])
		while(s[top+1]!=u){
			f[s[top]]=u;
			ins[s[top--]]=false; 
		}
}
int to[N],q[N],h,t;
inline void topo(){
	int u;h=1;
	for(int i=1;i<=n;++i)
		if(!to[i]) q[++t]=i;
	while(h<=t){
		u=q[h++];
		for(int i=g[u];i;i=e[i].nxt)
			if(!(--to[e[i].to])) q[++t]=e[i].to;
	}
}
inline void func(int b,int end){
	for(int i=1;i<=n;++i)
		a[i].reset();
	for(int i=b;i<=end;++i)
		a[i][i-b+1]=1;
	for(int i=t;i;--i)
		for(int j=g[q[i]];j;j=e[j].nxt)
			a[q[i]]|=a[e[j].to]; 
}
inline void Aireen(){
	n=read();m=read();
	for(int i=1;i<=m;++i){
		l[i]=read();r[i]=read();
		addedge(l[i],r[i]); 
	}
	cnt=0;
	for(int i=1;i<=n;++i)
		if(!dfn[i]) tarjan(i);
	memset(g,0,sizeof(g));cnt=0;
	for(int i=1;i<=m;++i)
		if(f[l[i]]!=f[r[i]]){
			addedge(f[l[i]],f[r[i]]);++to[r[i]];
		}
	topo();
	k=read();
	for(int i=1;i<=k;++i){
		x[i]=read();y[i]=read();
		if(f[x[i]]==f[y[i]]){
			puts("NO");return;
		}
	}
	for(int i=0;i*M+1<=n;++i){
		func(i*M+1,(i+1)*M); 
		for(int j=1;j<=k;++j)
			if(y[j]>i*M&&y[j]<=(i+1)*M&&a[x[j]][y[j]-i*M]){
				puts("NO");return;
			}
	}
	puts("YES"); 
	printf("%d\n",m);
	for(int i=1;i<=m;++i)
		printf("%d %d\n",l[i],r[i]);
}
int main(){
	freopen("gplt.in","r",stdin);
	freopen("gplt.out","w",stdout);
	Aireen();
	fclose(stdin);
	fclose(stdout);
	return 0;
}