Submission #960564

#	Time	Username	Problem	Language	Result	Execution time	Memory
960564		Champ_Naman	Olympic Bus (JOI20_ho_t4)	C++17	100 / 100	423 ms	6892 KiB

ho_t4

#include<bits/stdc++.h>
#define int long long
#define nl endl
using namespace std;

multiset<pair<int,int> > graph[201];

int Dijkstra(int u, int v){
    priority_queue<pair<int,int>, vector<pair<int,int> >, greater<pair<int,int> > > pq;
    vector<int> vis(201, 0);
    vector<int> dist(201, 1e18);

    dist[u] = 0;
    pq.push(make_pair(0, u));

    while(!pq.empty()){
        int p = pq.top().second;
        int dis = pq.top().first;
        pq.pop();

        if(vis[p]) continue;
        vis[p] = 1;

        for(auto ch : graph[p]){
            if(dis + ch.second < dist[ch.first]){
                dist[ch.first] = dis + ch.second;
                pq.push(make_pair(dist[ch.first], ch.first));
            }
        }
    }

    return dist[v];
}

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

    int n, m;
    cin>>n>>m;

    vector<vector<int> > dist(n+1, vector<int>(n+1, 1e18));
    int U[m], V[m], c[m], d[m];
    for(int i=0; i<m; i++){
        cin>>U[i]>>V[i]>>c[i]>>d[i];
        graph[U[i]].insert(make_pair(V[i], c[i]));
        dist[U[i]][V[i]] = min(c[i], dist[U[i]][V[i]]);
    }
    for(int i=1; i<=n; i++) dist[i][i] = 0;

    for(int k=1; k<=n; k++){
        for(int i=1; i<=n; i++){
            for(int j=1; j<=n; j++){
                dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
            }
        }
    }

    int ans = dist[1][n] + dist[n][1];
    //cout<<ans<<nl;
    for(int i=0; i<m; i++){
        int u = U[i], v = V[i];
        if(min(dist[1][n], dist[1][v] + c[i] + dist[u][n]) + min(dist[n][1], dist[n][v] + c[i] + dist[u][1]) + d[i] >= ans) continue;

        graph[u].erase(graph[u].find(make_pair(v, c[i])));
        graph[v].insert(make_pair(u, c[i]));

        ans = min(ans, Dijkstra(1, n) + Dijkstra(n, 1) + d[i]);
        //cout<<i<<" "<<Dijkstra(1, n) + Dijkstra(n, 1) + d[i]<<nl;

        graph[u].insert(make_pair(v, c[i]));
        graph[v].erase(graph[v].find(make_pair(u, c[i])));
    }

    if(ans >= 1e18) cout<<-1;
    else cout<<ans;
}

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