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| #include<bits/stdc++.h>
using namespace std;
int n,m;
int u[4000001];
int v[4000001];
bool vis[2000001];
int d[2000001];
int nxt[2000001];
int dfn[2000001];
int low[2000001];
int tot;
inline void add(int x,int y)
{
u[++tot]=x;
v[tot]=y;
nxt[tot]=d[x];
d[x]=tot;
return ;
}
int cnt;
int ans;
int st[2000001];
int group[2000001];
int sum=0;
inline void tarjan(int now)
{
low[now]=dfn[now]=++cnt;
st[++st[0]]=now;
vis[now]=1;
for(int i=d[now];i;i=nxt[i])
{
if(!dfn[v[i]])
{
tarjan(v[i]);
low[now]=min(low[now],low[v[i]]);
}
else
{
if(vis[v[i]])
{
low[now]=min(low[now],dfn[v[i]]);
}
}
}
if(dfn[now]==low[now])
{
sum++;
while(st[st[0]]!=now)
{
vis[st[st[0]]]=0;
group[st[st[0]]]=sum;
st[0]--;
}
vis[st[st[0]]]=0;
group[st[st[0]]]=sum;
st[0]--;
}
}
bool used[2000001];
int main()
{
cin>>n>>m;
for(int i=1;i<=m;i++)
{
int x,typex,y,typey;
cin>>x>>typex>>y>>typey;
add(x+n*(typex^1),y+n*typey);
add(y+n*(typey^1),x+n*typex);
}
for(int i=1;i<=2*n;i++)
{
if(!dfn[i])
{
tarjan(i);
}
}
memset(d,0,sizeof(d));
tot=0;
for(int i=1;i<=2*m;i++)
{
if(group[u[i]]!=group[v[i]])
{
add(group[u[i]],group[v[i]]);
}
}
for(int i=1;i<=n;i++)
{
if(group[i]==group[i+n])
{
cout<<"IMPOSSIBLE"<<endl;
return 0;
}
}
cout<<"POSSIBLE"<<endl;
for(int i=1;i<=n;i++)
{
if(used[group[i]])
{
cout<<0<<" ";
}
else if(used[group[i+n]])
{
cout<<1<<" ";
}
else if(group[i]<group[i+n])
{
cout<<0<<" ";
used[group[i]]=1;
}
else
{
cout<<1<<" ";
used[group[i+n]]=1;
}
}
return 0;
}
|