2025牛客暑期多校训练营1—K.Museum Acceptance（分层图，把一个点分为多个点）

思路讲解

非常暴力的模拟，唯一记忆的地方就在于这个划线。

FOR(i,1,N){
	if(ans[i][1]!=0){
		cout<<ans[i][1]<<"\n";
		continue;
	}
	ll cur=i,id=1;
	vector<arr2> wp;
	while(true){
		wp.pb({cur,id});
		ll v=g[cur][id];
		FOR(i,1,num[v]){
			if(g[v][i]==cur){
				id=i;
			}
		}
		if(id+1<=num[v]){
			id+=1;
		}else{
			id=1;
		}
		if(ans[v][id]){
			ll lans=ans[v][id]+SZ(st);
			if(ans[v][id]==-1) lans=SZ(st);
			for(auto &[x,idx]:wp){
				ans[x][idx]=lans;
			}
			break;
		}
		ans[v][id]=-1;
		arr2 t={cur,v};sort(all(t));
		st.insert(t);
		cur=v;
	}
	cout<<ans[i][1]<<"\n";
	st.clear();
}

AC代码

https://ac.nowcoder.com/acm/contest/view-submission?submissionId=78205559

源代码

// Problem: Museum Acceptance
// Contest: NowCoder
// URL: https://ac.nowcoder.com/acm/contest/108298/K
// Memory Limit: 1024 MB
// Time Limit: 4000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
#define all(vec) vec.begin(),vec.end()
#define pb push_back
#define SZ(a) ((int) a.size())
#define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define ROF(i, a, b) for (int i = (a); i >= (b); --i)
#define debug(var) cerr << #var <<":"<<var<<"\n";
#define lson(var) (var<<1)
#define rson(var) ((var<<1)+1)

using namespace std;

using  ll = long long;using ull = unsigned long long;
using DB=double;using LD=long double;
// using i128 = __int128;
using pdd = pair<DB,DB>;using plb = pair<ll,bool>;
using pll = pair<ll,ll>;
using arr3 = array<ll,3> ;using arr2 = array<ll,2>;
constexpr ll MAXN=static_cast<ll>(1e6)+10,INF=static_cast<ll>(1e17)+9; // 1e18+9也是素数
constexpr ll MAXM=(ll)1e6+10;constexpr ll MAXV=(ll)1e6+10;
constexpr ll mod=static_cast<ll>(1e9)+7;
constexpr double eps=1e-8;const double pi=acos(-1.0);

ll N,M,Q,X,K,T,lT,A[MAXN];
/*

*/
ll num[MAXN];
ll g[MAXN][5];
ll fa[MAXN];
ll ans[MAXN][5];
ll find(ll x){
	if(fa[x]==x) return fa[x];
	return fa[x]=find(fa[x]);
}
void merge(ll a,ll b){
	ll pa=find(a),pb=find(b);
	fa[pa]=pb;
}
inline void __(){
	cin>>N;
	FOR(i,1,N){
		fa[i]=i;
	}
	FOR(i,1,N){
		cin>>num[i];
		FOR(j,1,num[i]){
			cin>>g[i][j];
		}
	}
	// unordered_map<pll,bool> st;
	// unordered_map<pll,bool> s;
	// FOR(i,1,N){
		// FOR(j,1,num[i]){
			// s[(pll){i,j}]=false;
		// }
	// }
	set<arr2> st;
#ifdef LOCAL
    cerr << "OK1" << '\n';
#endif
	FOR(i,1,N){
		if(ans[i][1]!=0){
			cout<<ans[i][1]<<"\n";
			continue;
		}
		ll cur=i,id=1;
		vector<arr2> wp;
		while(true){
			wp.pb({cur,id});
			ll v=g[cur][id];
			FOR(i,1,num[v]){
				if(g[v][i]==cur){
					id=i;
				}
			}
			if(id+1<=num[v]){
				id+=1;
			}else{
				id=1;
			}
			if(ans[v][id]){
				ll lans=ans[v][id]+SZ(st);
				if(ans[v][id]==-1) lans=SZ(st);
				for(auto &[x,idx]:wp){
					ans[x][idx]=lans;
				}
				break;
			}
			ans[v][id]=-1;
			arr2 t={cur,v};sort(all(t));
			st.insert(t);
			cur=v;
		}
		cout<<ans[i][1]<<"\n";
		st.clear();
	}
#ifdef LOCAL
    FOR(i,1,N){
		FOR(j,1,3){
			cerr<<ans[i][j]<<" ";
		}
		cerr<<"\n";
	}
#endif
	
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	
	// cin>>lT;
	// while(lT--)
		__();
	return 0;
}
/*

*/

心路历程（WA，TLE，MLE……）