Submission #502472

#	Time	Username	Problem	Language	Result	Execution time	Memory
502472		zorianka	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	716 ms	36632 KiB

commuter_pass

//#pragma GCC optimize("O3")

#include <bits/stdc++.h>

using namespace std;
#define MAXN 100005
#define MAXM 100005
#define mix(a, b) a = min(a,b)
using ll = long long;
const ll mod = 1e9 + 7;

vector<pair<int, ll>> g[MAXN];
vector<pair<int, ll>> gc[MAXN];
vector<ll> ds, dt;
ll st;

void dijkstra(vector<ll> &dist, int s) {
    dist[s] = 0;
    set<pair<ll, int>> q;
    q.insert({0, s});
    while (!q.empty()) {
        int v = q.begin()->second;
        q.erase(q.begin());
        for (auto[u, c] : g[v]) {
            if (dist[v] + c < dist[u]) {
                q.erase({dist[u], u});
                dist[u] = dist[v] + c;
                q.insert({dist[u], u});
            }
        }
    }
}

void spec(vector<ll> &dist, int s) {
    dist[s] = 0;
    set<pair<ll, int>> q;
    q.insert({0, s});
    vector<int> flex(dist.size(), false);
    vector<int> parent(dist.size(), -1);
    parent[s] = s;
    while (!q.empty()) {
        int v = q.begin()->second;
        q.erase(q.begin());
        if (flex[v] == 0 && flex[parent[v]] != 0) flex[v] = 2;
        for (auto[u, c] : g[v]) {
            if (ds[v] < ds[u] && flex[v] != 2)
                if (ds[v] + c + dt[u] == st)
                    c = 0;
            if (dist[v] + c < dist[u]) {
                q.erase({dist[u], u});
                dist[u] = dist[v] + c;
                parent[u] = v;
                if (c == 0) flex[u] = true;
                q.insert({dist[u], u});
            }
        }
    }
}

void solve() {
    int n, m;
    cin >> n >> m;
    int s, t;
    cin >> s >> t;
    int u, v;
    cin >> u >> v;
    for (int i = 0; i < m; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        g[a].emplace_back(b, c);
        g[b].emplace_back(a, c);
        gc[a].emplace_back(b, c);
        gc[b].emplace_back(a, c);
    }
    ds.resize(n + 1, 1e18), dt.resize(n + 1, 1e18);
    dijkstra(ds, s);
    dijkstra(dt, t);
    st = ds[t];
    vector<ll> bebra(n + 1, 1e18);
    spec(bebra, u);
    ll ans = bebra[v];
    bebra.assign(n + 1, 1e18);
    spec(bebra, v);
    ans = min(ans, bebra[u]);
    cout << ans;
}

signed main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
//    cin >> t;
    while (t--)
        solve();
    return 0;
}

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