Submission #700183

#	Time	Username	Problem	Language	Result	Execution time	Memory
700183		berr	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	408 ms	36080 KiB

commuter_pass

// 1 
#include <bits/stdc++.h>
using namespace std; 

#define int long long
const int N = 1e5+37;
vector<array<int, 2>> adj[N];
vector<int> ds, dt, dv, du, adj2[N];
vector<array<int, 2>> a1(N), a2(N);

vector<int> d(int x){
    vector<int> dist(N, 1e18);
    dist[x] = 0;
    priority_queue<array<int, 2>> q;

    q.push({0, x});

    while (q.size()){
        int u = -q.top()[0], v = q.top()[1];
        q.pop();
        for (auto i: adj[v]){
            if(dist[i[0]] > u+i[1]){
                dist[i[0]] = u + i[1];
                q.push({-dist[i[0]], i[0]});
            }
        }
    }

    return dist;
}

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

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

    int s, t, u, v; cin >> s >> t >> u >> v;
    s--; t--; u--; v--;

    vector<array<int, 3>> e;

    for (int i = 0; i < m; i++){
        int x, y, z; cin >> x >> y >> z;
        x--; y--;
        adj[x].push_back({y, z});
        adj[y].push_back({x, z});
        e.push_back({x, y, z});
    }

    ds=d(s), dt=d(t), du=d(u), dv=d(v);

    for (auto i: e){
        if(i[2] + ds[i[0]] + dt[i[1]] == ds[t]) adj2[i[0]].push_back(i[1]), adj2[i[1]].push_back(i[0]);
        if(i[2] + ds[i[1]] + dt[i[0]] == ds[t]) adj2[i[0]].push_back(i[1]), adj2[i[1]].push_back(i[0]);
    }

    int a=1e18;


    for (int i = 0; i < n; i++){
        a1[i] = {a, a};
        a2[i] = {a, a};
    }

    queue<int> q;

    q.push(s);
    vector<int> vis(n);
    vis[s]=1;

    while (q.size()){
        int c=q.front();
        q.pop();
        a1[c][0] = min(a1[c][0], dv[c]);
        a1[c][1] = min(a1[c][1], du[c]);

        for (auto i: adj2[c]){
            if(ds[i] > ds[c]){
                a1[i][0] = min(a1[i][0], a1[c][0]);
                a1[i][1] = min(a1[i][1], a1[c][1]);
                if(vis[i]==0) q.push(i), vis[i]=1;
            }
        }
    }

    q.push(t);

    for(int i=0; i<n; i++) vis[i]=0;

    vis[t]=1;

    while (q.size()){
        int c=q.front();
        q.pop();
        a2[c][0] = min(a2[c][0], dv[c]);
        a2[c][1] = min(a2[c][1], du[c]);

        for (auto i: adj2[c]){
            if(dt[i] > dt[c]){
                a2[i][0] = min(a2[i][0], a2[c][0]);
                a2[i][1] = min(a2[i][1], a2[c][1]);
                if(vis[i]==0) q.push(i), vis[i]=1;
            }
        }
    }

    int ans=dv[u];



    for(int i=0; i<n; i++){
        ans = min({a1[i][0] + a2[i][1], a1[i][1] + a2[i][0], ans});
    }

    cout<<ans;
}

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45