题解
很抽象的建模,我一开始想的是韦恩图,然后韦恩图里选取 若干 个点,还要保证每个图都能选上,然后把韦恩图抽象成点,图中的点抽象成待匹配的点,然后就是二分图匹配了
code
#include<bits/stdc++.h>
#define ll long long
#define lb long double
#define lowbit(x) ((x)&(-x))
using namespace std;
const ll inf=1e18;
const ll mod=1e9+7;
const ll N=4e5;
ll qpow(ll a,ll n)
{
ll res=1;
while(n)
{
if(n&1) res=res*a%mod;
a=a*a%mod;
n>>=1;
}
return res;
}
ll inv(ll x)
{
return qpow(x,mod-2);
}
ll fa[2000005];
ll finds(ll now){return now==fa[now]?now:finds(fa[now]);}
vector<ll> G[200005];
ll dfn[200005],low[200005];
ll cnt=0,num=0;
ll in_st[200005]={0};
stack<ll> st;
ll belong[200005]={0};
void scc(ll now,ll fa)
{
dfn[now]=++cnt;
low[now]=dfn[now];
in_st[now]=1;
st.push(now);
for(auto next:G[now])
{
if(next==fa) continue;
if(!dfn[next])
{
scc(next,now);
low[now]=min(low[now],low[next]);
}
else if(in_st[next])
{
low[now]=min(low[now],dfn[next]);
}
}
if(low[now]==dfn[now])
{
ll x;
num++;
do
{
x=st.top();
st.pop();
in_st[x]=0;
belong[x]=num;
}while(x!=now);
}
}
ll match[1005]={0};
ll vis[1005]={0};
bool zhao(ll now)
{
for(auto next:G[now])
{
if(vis[next]) continue;
vis[next]=1;
if(!match[next]||zhao(match[next]))
{
match[next]=now;
return 1;
}
}
return 0;
}
ll need[1005];
void solve()
{
ll k,n;
cin>>k>>n;
for(ll i=1;i<=k;i++) cin>>need[i];
for(ll i=1;i<=n;i++)
{
ll x;
cin>>x;
for(ll j=1;j<=x;j++)
{
ll y;
cin>>y;
G[y].push_back(i);
}
}
for(ll i=1;i<=k;i++)
{
memset(vis,0,sizeof vis);
ll cnt=0;
for(ll j=1;j<=need[i];j++)
{
if(zhao(i)) cnt++;
}
if(cnt!=need[i])
{
cout<<"No Solution!";
return;
}
}
vector<ll> ans[k+1];
for(ll i=1;i<=n;i++)
{
if(match[i])
{
ans[match[i]].push_back(i);
}
}
for(int i=1;i<=k;i++)
{
cout<<i<<": ";
for(auto it:ans[i]) cout<<it<<' ';
cout<<'\n';
}
}
int main()
{
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
int TT=1;
//cin>>TT;
while(TT--) solve();
return 0;
}
标签:return,试题库,ll,next,问题,low,st,P2763,now
From: https://www.cnblogs.com/pure4knowledge/p/18341636