Submission #960064

#	Time	Username	Problem	Language	Result	Execution time	Memory
960064		happy_node	Olympic Bus (JOI20_ho_t4)	C++17	100 / 100	820 ms	6100 KiB

ho_t4

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

const int MX=5e4+5;

int N,M;
ll U[MX], V[MX], C[MX], D[MX];
pair<ll, ll> dist[205][205], DIST[205];

vector<array<ll,3>> adj[205];
vector<ll> edges[205], redges[205];

bool crucial[MX], rcrucial[MX];

int main() {
	cin.tie(0); ios_base::sync_with_stdio(0);

	for(int i=0;i<205;i++)
		for(int j=0;j<205;j++)
			dist[i][j]=make_pair(2e9,2e9);

	cin>>N>>M;

	for(int i=0;i<M;i++) {
		cin>>U[i]>>V[i]>>C[i]>>D[i];
		adj[U[i]].push_back({V[i],C[i],i});
	}

	for(int s=1;s<=N;s++) {
		priority_queue<pair<pair<ll,ll>,ll>, vector<pair<pair<ll,ll>,ll>>, greater<pair<pair<ll,ll>,ll>>> pq;

		dist[s][s]=make_pair(0,0);
		pq.push({dist[s][s],s});

		while(!pq.empty()) {
			auto [d,v]=pq.top(); pq.pop();
			if(d>dist[s][v]) continue;
			for(auto [u,w,id]:adj[v]) {
				if(dist[s][u]>make_pair(d.first+w,d.second+1)) {
					dist[s][u]=make_pair(d.first+w,d.second+1);
					pq.push({dist[s][u],u});
				}
			}
		}
	}

	for(int i=0;i<M;i++) {
		int u=U[i],v=V[i],c=C[i];
		if(make_pair(dist[1][u].first+dist[v][N].first+c,dist[1][u].second+dist[v][N].second+1)==dist[1][N]) {
			edges[dist[1][u].second+1].push_back(i);
		}
	}

	for(int i=0;i<M;i++) {
		int u=U[i],v=V[i],c=C[i];
		if(make_pair(dist[N][u].first+dist[v][1].first+c,dist[N][u].second+dist[v][1].second+1)==dist[N][1]) {
			redges[dist[N][u].second+1].push_back(i);
		}
	}


	for(int d=1;d<=N;d++) {
		if(edges[d].size()==1) {
			crucial[edges[d][0]]=1;
		}
		if(redges[d].size()==1) {
			rcrucial[redges[d][0]]=1;
		}
	}

	ll ans=2e9;
	if(dist[1][N].first!=2e9 && dist[N][1].first!=2e9) ans=min(ans,dist[1][N].first+dist[N][1].first);

	for(int i=0;i<M;i++) {
		ll cost=2e9,rcost=2e9;
		ll u=U[i],v=V[i],c=C[i],d=D[i];

		if(crucial[i])  {
			priority_queue<pair<pair<ll,ll>,ll>, vector<pair<pair<ll,ll>,ll>>, greater<pair<pair<ll,ll>,ll>>> pq;

			for(int i=1;i<=N;i++) DIST[i]=make_pair(2e9,2e9);

			DIST[1]=make_pair(0,0);
			pq.push({DIST[1],1});

			while(!pq.empty()) {
				auto [d,v]=pq.top(); pq.pop();
				if(d>DIST[v]) continue;
				for(auto [u,w,id]:adj[v]) {
					if(id==i) continue;
					if(DIST[u]>make_pair(d.first+w,d.second+1)) {
						DIST[u]=make_pair(d.first+w,d.second+1);
						pq.push({DIST[u],u});
					}
				}
				// new edge
				if(v==V[i]) {
					int u=U[i];
					if(DIST[u]>make_pair(d.first+c,d.second+1)) {
						DIST[u]=make_pair(d.first+c,d.second+1);
						pq.push({DIST[u],u});
					}
				}
			}
			cost=min(cost,DIST[N].first);
		} else {
			cost=min(cost,dist[1][v].first+c+dist[u][N].first);
			cost=min(cost,dist[1][N].first);
		}

		if(rcrucial[i])  {
			priority_queue<pair<pair<ll,ll>,ll>, vector<pair<pair<ll,ll>,ll>>, greater<pair<pair<ll,ll>,ll>>> pq;

			for(int i=1;i<=N;i++) DIST[i]=make_pair(2e9,2e9);

			DIST[N]=make_pair(0,0);
			pq.push({DIST[N],N});

			while(!pq.empty()) {
				auto [d,v]=pq.top(); pq.pop();
				if(d>DIST[v]) continue;
				for(auto [u,w,id]:adj[v]) {
					if(id==i) continue;
					if(DIST[u]>make_pair(d.first+w,d.second+1)) {
						DIST[u]=make_pair(d.first+w,d.second+1);
						pq.push({DIST[u],u});
					}
				}
				// new edge
				if(v==V[i]) {
					int u=U[i];
					if(DIST[u]>make_pair(d.first+c,d.second+1)) {
						DIST[u]=make_pair(d.first+c,d.second+1);
						pq.push({DIST[u],u});
					}
				}
			}
			rcost=min(rcost,DIST[1].first);
		} else {
			rcost=min(rcost,dist[N][v].first+c+dist[u][1].first);
			rcost=min(rcost,dist[N][1].first);
		}

		ans=min(ans,d+cost+rcost);
	}

	cout<<(ans==2e9?-1:ans)<<'\n';
}

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 63 / 63