Submission #1266540

#	Time	Username	Problem	Language	Result	Execution time	Memory
1266540		vlomaczk	Olympic Bus (JOI20_ho_t4)	C++20	0 / 100	104 ms	4792 KiB

ho_t4

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

struct Edge {
	ll a, b, c, d;
};

ll M = 201, inf=1e18;
ll n, m;
vector<vector<ll>> g(M), gt(M), D(M, vector<ll>(M, inf)), C(M, vector<ll>(M, inf)), used(2, vector<ll>(50'001));
vector<Edge> e;

ll dijkstra1(ll s, ll z) {
	ll koniec = (z ? 1 : n);
	vector<ll> dist(M, inf), par(M, -1);
	vector<ll> vis(M, 0);
	dist[s] = 0;
	for(int i=0; i<n; ++i) {
		int v = 0;
		for(int x=1; x<=n; ++x) {
			if(!vis[x] && dist[x] < dist[v]) v = x;
		}
		if(dist[v] == inf) break;
		vis[v] = 1;
		for(auto k : g[v]) {
			int u = e[k].b;
			if(dist[v] + e[k].c < dist[u]) {
				dist[u] = dist[v] + e[k].c;
				if(par[u]!=-1) used[z][par[u]] = 0;
				used[z][k] = 1;
				par[u] = k;
			}
		}
	}
	return dist[koniec];
}

ll dijkstra2(ll s, ll koniec, ll z) {
	vector<ll> dist(M, inf);
	vector<ll> vis(M, 0);
	dist[s] = 0;
	for(int i=0; i<n; ++i) {
		int v = 0;
		for(int x=1; x<=n; ++x) {
			if(!vis[x] && dist[x] < dist[v]) v = x;
		}
		if(dist[v] == inf) break;
		vis[v] = 1;
		for(auto k : g[v]) {
			if(k==z) continue;
			int u = e[k].b;
			if(dist[v] + e[k].c < dist[u]) dist[u] = dist[v] + e[k].c;
		}
		for(auto k : gt[v]) {
			if(k!=z) continue;
			int u = e[k].a;
			if(dist[v] + e[k].c < dist[u]) dist[u] = dist[v] + e[k].c;
		}
	}
	return dist[koniec];
}

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

	cin >> n >> m;
	for(int i=1; i<=n; ++i) D[i][i] = 0;
	for(int i=0; i<m; ++i) {
		ll a, b, c, d;
		cin >> a >> b >> c >> d;
		e.push_back({a, b, c, d});
		D[a][b] = min(D[a][b], c);
		g[a].push_back(i);
		gt[b].push_back(i);
	}
	for(int k=1; k<=n; ++k) for(int i=1; i<=n; ++i) for(int j=1; j<=n; ++j) D[i][j] = min(D[i][j], D[i][k] + D[k][j]);
	for(int i=1; i<=n; ++i) for(int j=1; j<=n; ++j) C[i][j] = (D[i][j]<inf);
	ll v0 = dijkstra1(1, 0);
	ll v1 = dijkstra1(n, 1);
	ll ans = inf;
	for(auto[a,b,c,d] : e) {
		ans = min(ans, D[1][b] + D[a][n] + D[n][b] + D[a][1] + 2*c + d);
	}
	if(C[1][n]) {
		for(int i=0; i<m; ++i) {
			auto[a,b,c,d] = e[i];
			if(used[0][i]) {
				ans = min(ans, D[n][b] + c + d + D[a][1] + dijkstra2(1, n, i));
			} else {
				ans = min(ans, D[n][b] + c + d + D[a][1] + v0);
			}
		}
	}
	if(C[n][1]) {
		for(int i=0; i<m; ++i) {
			auto[a,b,c,d] = e[i];
			if(used[1][i]) {
				ans = min(ans, D[1][b] + c + d + D[a][n] + dijkstra2(n, 1, i));
			} else {
				ans = min(ans, D[1][b] + c + d + D[a][n] + v1);
			}
		}
	}

	if(ans < inf) cout << ans << "\n";
	else cout << "-1\n";

	return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 63