제출 #758908

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
758908		xyzxyz	Olympic Bus (JOI20_ho_t4)	C++17	37 / 100	1076 ms	6316 KiB

ho_t4

#include<bits/stdc++.h>

using namespace std;

vector<int> kosten;

void dijkstra(vector<set<pair<int,int>>>& adj, vector<long long>& dist, int start, vector<pair<int,int>>&parent){
    priority_queue<pair<long long,int>, vector<pair<long long,int>>, greater<pair<long long,int>>> pq;
    dist[start] = 0;
    pq.push({0,start});
    while(!pq.empty()){
        long long wo = pq.top().second, preis = pq.top().first;
        pq.pop();
        if(dist[wo]== preis){
            for(auto[ziel, index]: adj[wo]){
                if(dist[ziel] > kosten[index]+preis){
                    dist[ziel] = kosten[index]+preis;
                    parent[ziel] = {wo, index};
                    pq.push({dist[ziel], ziel});
                }
            }
        }
    }
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int v, e; cin >> v >> e;
    vector<set<pair<int,int>>> adj(v), adj2(v);
    vector<tuple<int,int,int,int>> edges(e);
    vector<int> umdrehkosten(e);
    kosten = vector<int>(e);
    for(int i=0; i<e; i++){
        int a, b; cin >> a >> b >> kosten[i] >> umdrehkosten[i];
        a--; b--;
        adj[a].insert({b, i});
        adj2[b].insert({a, i});//umgedrehter Graph
        edges[i] = make_tuple(a,b,kosten[i],umdrehkosten[i]);
    }
    vector<long long> von0(v, 1e17), vonn_r(v, 1e17), vonn(v, 1e17), von0_r(v, 1e17);
    vector<pair<int,int>> parent0(v, {-1, -1}), parent2(v, {-1, -1}), parentn(v, {-1, -1});
    dijkstra(adj, von0, 0, parent0);
    dijkstra(adj2, vonn_r, v-1, parent2);
    dijkstra(adj2, von0_r, 0, parent2);
    dijkstra(adj, vonn, v-1, parentn);
    int ort = v-1;
    vector<bool> used(e, false);
    while(parent0[ort].first!=-1){
        used[parent0[ort].second] = true;
        ort = parent0[ort].first;
    }
    ort = 0;
    while(parentn[ort].first!=-1){
        used[parentn[ort].second] = true;
        ort = parentn[ort].first;
    }
    long long res = min((long long)1e17, (long long)von0[v-1]+vonn[0]);//keine Kante gedreht
    for(int i=0; i<e; i++){
        auto [start, ende, cost, r_cost] = edges[i];
        if(used[i]){
            adj[start].erase({ende, i});
            adj[ende].insert({start, i});
            vector<long long> dist(v, 1e17), dist2(v, 1e17);
            dijkstra(adj, dist, 0, parent0);
            dijkstra(adj, dist2, v-1, parent0);
            res = min(res, dist[v-1]+dist2[0]+r_cost);
            adj[start].insert({ende, i});
            adj[ende].erase({start, i});
        }else{
            long long a = min(vonn[0], vonn[ende] + cost + von0_r[start]);
            long long b = min(von0[v-1], von0[ende] + cost + vonn_r[start]);
            res = min(res, a + b + r_cost);
        }
    }
    if(res!=1e17) cout << res;
    else cout << -1;
    return 0;
}

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