Submission #1133477

#	Time	Username	Problem	Language	Result	Execution time	Memory
1133477		vladilius	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	322 ms	25128 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pli = pair<ll, int>;
#define pb push_back
#define ff first
#define ss second
const ll inf = 1e18;

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    int n, m, s, t, u, v; cin>>n>>m>>s>>t>>u>>v;
    vector<pii> g[n + 1];
    while (m--){
        int x, y, w; cin>>x>>y>>w;
        g[x].pb({y, w});
        g[y].pb({x, w});
    }
    
    auto f = [&](int x){
        vector<ll> out(n + 1, inf);
        priority_queue<pli, vector<pli>, greater<pli>> pq;
        out[x] = 0; pq.push({0, x});
        while (!pq.empty()){
            auto [d, y] = pq.top(); pq.pop();
            for (auto [i, w]: g[y]){
                ll dd = d + w;
                if (dd < out[i]){
                    out[i] = dd;
                    pq.push({out[i], i});
                }
            }
        }
        return out;
    };
    
    vector<ll> d[n + 1];
    d[s] = f(s);
    d[t] = f(t);
    d[u] = f(u);
    d[v] = f(v);
    
    vector<int> G[n + 1];
    for (int i = 1; i <= n; i++){
        for (auto [j, w]: g[i]){
            if (d[s][t] == (d[s][i] + w + d[t][j])){
                G[i].pb(j);
            }
        }
    }
    
    vector<bool> used(n + 1);
    vector<ll> sz1(n + 1, inf), sz2(n + 1, inf);
    ll out = d[u][v];
    function<void(int)> dfs = [&](int x){
        used[x] = 1;
        sz1[x] = d[u][x];
        sz2[x] = d[v][x];
        for (int i: G[x]){
            if (!used[i]){
                dfs(i);
            }
            sz1[x] = min(sz1[x], sz1[i]);
            sz2[x] = min(sz2[x], sz2[i]);
        }
        
        out = min(out, d[u][x] + sz2[x]);
        out = min(out, d[v][x] + sz1[x]);
    };
    dfs(s);
    
    cout<<out<<"\n";
}

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