Submission #729400

#	Time	Username	Problem	Language	Result	Execution time	Memory
729400		Pring	Commuter Pass (JOI18_commuter_pass)	C++14	16 / 100	1480 ms	262144 KiB

commuter_pass

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

#define int long long
typedef pair<int, int> pii;

const int MXN = 100005;
// int n, m, s, t, u, v, father[MXN], du[MXN], dv[MXN], uu = LLONG_MAX, vv = LLONG_MAX;
int n, m, s, t, u, v, ds[MXN], du[MXN], dv[MXN], ans = LLONG_MAX, uu = LLONG_MAX, vv = LLONG_MAX;
vector<pii> edge[MXN];
vector<int> path, father[MXN];
set<int> reach[MXN];
bool B = false;
bitset<MXN> b;

void GET_PATH() {
    b.reset();
    priority_queue<pair<int, pii>, vector<pair<int, pii>>, greater<pair<int, pii>>> pq;
    pq.push({0, {s, s}});
    while (pq.size()) {
        pair<int, pii> now = pq.top();
        pq.pop();
        // if (b[now.second.second]) continue;
        if (b[now.second.second]) {
            if (ds[now.second.second] == now.first) father[now.second.second].push_back(now.second.first);
            continue;
        }
        b[now.second.second] = true;
        // father[now.second.second] = now.second.first;
        ds[now.second.second] = now.first;
        father[now.second.second].push_back(now.second.first);
        for (auto &i : edge[now.second.second]) {
            if (b[i.first]) continue;
            pq.push({now.first + i.second, {now.second.second, i.first}});
        }
    }
    // int now = t;
    // path.push_back(now);
    // while (now != s) {
    //     now = father[now];
    //     path.push_back(now);
    // }
    b.reset();
    queue<int> q;
    q.push(t);
    while (q.size()) {
        int now = q.front();
        q.pop();
        if (b[now]) {
            if (now == s) continue;
            B = true;
            continue;
        }
        b[now] = true;
        path.push_back(now);
        for (auto &i : father[now]) {
            if (b[i]) continue;
            q.push(i);
        }
    }
}

void DIJKSTRA(int start, int *arr) {
    b.reset();
    priority_queue<pii, vector<pii>, greater<pii>> pq;
    pq.push({0, start});
    while (pq.size()) {
        pii now = pq.top();
        pq.pop();
        if (b[now.second]) continue;
        b[now.second] = true;
        arr[now.second] = now.first;
        for (auto &i : edge[now.second]) {
            if (b[i.first]) continue;
            pq.push({now.first + i.second, i.first});
        }
    }
}

void GET_REACH(int id) {
    queue<int> q;
    q.push(id);
    while (q.size()) {
        int now = q.front();
        q.pop();
        // if (b[now]) {
        //     continue;
        // }
        // b[now] = true;
        if (!reach[id].insert(now).second) continue;
        // path.push_back(now);
        for (auto &i : father[now]) {
            q.push(i);
        }
    }
}

int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int x, y, z;
    cin >> n >> m >> s >> t >> u >> v;
    for (int i = 0; i < m; i++) {
        cin >> x >> y >> z;
        edge[x].push_back({y, z});
        edge[y].push_back({x, z});
    }
    // GET_PATH();
    GET_PATH();
    if (s == u) {
        DIJKSTRA(v, dv);
        for (auto &i : path) {
            // cout << i << endl;
            ans = min(ans, dv[i]);
        }
        cout << ans << endl;
    } else if (B) {
        DIJKSTRA(u, du);
        DIJKSTRA(v, dv);
        for (auto &i : path) {
            uu = min(uu, du[i]);
            vv = min(vv, dv[i]);
        }
        cout << min(du[v], uu + vv) << endl;
    } else {
        DIJKSTRA(u, du);
        DIJKSTRA(v, dv);
        ans = du[v];
        for (auto &i : path) GET_REACH(i);
        for (auto &i : path) {
            for (auto &j : path) {
                if (reach[i].count(j) || reach[j].count(i)) {
                    ans = min(ans, du[i] + dv[j]);
                    ans = min(ans, du[j] + dv[i]);
                }
            }
        }
        cout << ans << endl;
    }
    return 0;
}

• Subtask 1: 16 / 16
• Subtask 2: 0 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45