Submission #729438

#	Time	Username	Problem	Language	Result	Execution time	Memory
729438		Pring	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	498 ms	39564 KiB

commuter_pass

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

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

const int MXN = 100005;
int n, m, s, t, u, v, ds[MXN], du[MXN], dv[MXN], ans = LLONG_MAX, dp[2][MXN];
vector<pii> edge[MXN];
vector<int> L[MXN], R[MXN], father[MXN];
bitset<MXN> b;

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

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

void BFS() {
    b.reset();
    priority_queue<pii, vector<pii>, greater<pii>> pq;
    pq.push({0, s});
    while (pq.size()) {
        pii now = pq.top();
        pq.pop();
        if (b[now.second]) continue;
        b[now.second] = true;
        dp[0][now.second] = LLONG_MAX;
        dp[1][now.second] = LLONG_MAX;
        for (auto &i : L[now.second]) {
            dp[0][now.second] = min(dp[0][now.second], dp[0][i]);
            dp[1][now.second] = min(dp[1][now.second], dp[1][i]);
        }
        dp[0][now.second] = min(dp[0][now.second], du[now.second]);
        dp[1][now.second] = min(dp[1][now.second], dv[now.second]);
        ans = min(ans, min(dp[0][now.second] + dv[now.second], dp[1][now.second] + du[now.second]));
        for (auto &i : R[now.second]) {
            if (b[i]) continue;
            pq.push({ds[i], 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();
    DIJKSTRA(u, du);
    DIJKSTRA(v, dv);
    ans = du[v];
    BFS();
    cout << ans << endl;
    return 0;
}

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