Submission #605635

#	Time	Username	Problem	Language	Result	Execution time	Memory
605635		Ronin13	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	531 ms	35264 KiB

commuter_pass

#include<bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define epb emplace_back
using namespace std;
const int NMAX = 1e5 + 1;
vector <vector <pll> > g(NMAX);
ll d[NMAX][4];
vector <vector <int> > p(NMAX);
void Dijkstra(int n, int s, int ind){
    d[s][ind] = 0;
    priority_queue <pll> q;
    q.push({0, s});
    vector <bool> used(n + 1);
    while(!q.empty()){
        int v = q.top().s;
        q.pop();
        if(used[v]) continue;
        used[v] = true;
        for(auto x : g[v]){
            int to = x.f;
            ll l = x.s;
            if(d[to][ind] > d[v][ind] + l){
                d[to][ind] = d[v][ind] + l;
                q.push({-d[to][ind], to});
                if(!ind){
                p[to].clear();
                p[to].pb(v);
                }
            }
            else{
                if(d[to][ind] == d[v][ind] + l){
                   if(!ind) p[to].pb(v);
                }
            }
        }
    }
}

vector <vector <int> > G(NMAX);
stack <int> st, st1;
vector <bool> used(NMAX, false);
void dfs(int v){
    used[v] = true;
    for(int to : G[v]){
        if(used[to]) continue;
        dfs(to);
    }
    st.push(v);
    st1.push(v);
}

int main(){
    int n, m; cin >> n >> m;
    int s, t; cin >> s >> t;
    int x, y; cin >> x >> y;
    for(int i = 1; i <= m; i++){
        int u, v;
        ll c;
        cin >> u >> v >> c;
        g[u].pb({v, c});
        g[v].pb({u, c});
    }
    for(int i = 1; i <= n; i++){
        for(int j = 0; j < 4; j++) d[i][j] = 1e18;
    }
    Dijkstra(n, s, 0);
    Dijkstra(n, t, 1);
    Dijkstra(n, x, 2);
    Dijkstra(n, y, 3);
    for(int i = 1; i <= n; i++){

        for(int to : p[i]) G[to].pb(i);
    }
    dfs(s);
    ll ans[n + 1];
    for(int i = 1; i <= n; i++){
        ans[i] = 1e18;
    }
    ll res = d[x][3];
    while(!st.empty()){
        int v = st.top();
        st.pop();
        if(d[t][0] != d[v][0] + d[v][1]) continue;
        ans[v] = min(d[v][2], ans[v]);
        res = min(res, ans[v] + d[v][3]);
        for(int to : G[v]){
            ans[to] = min(ans[to], ans[v]);
        }
    }
    for(int i = 1; i <= n; i++){
        ans[i] = 1e18;
    }
    while(!st1.empty()){
        int v = st1.top();
        st1.pop();
        if(d[t][0] != d[v][0] + d[v][1]) continue;
        ans[v] = min(d[v][3], ans[v]);
        res = min(res, ans[v] + d[v][2]);
        for(int to : G[v]){
            ans[to] = min(ans[to], ans[v]);
        }
    }
    cout << res;
    return 0;
}

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