Submission #1267195

#	Time	Username	Problem	Language	Result	Execution time	Memory
1267195		firegirlwaterboy	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	318 ms	27384 KiB

commuter_pass

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;

vector<pll> adj[100001];
ll du[100001], dv[100001], ds[100001], dp[2][100001], ans;
bool visited[100001];

void dijkstra1(ll start, ll arr[]) {
    fill(visited, visited + 100001, false);
    priority_queue<pll> pq;
    pq.push({0, start});
    while (!pq.empty()) {
        ll c, node;
        tie(c, node) = pq.top();
        pq.pop();
        if (visited[node]) continue;
        arr[node] = -c;
        visited[node] = true;
        for (auto &i : adj[node]) {
            pq.push({c - i.second, i.first});
        }
    }
}

void dijkstra2(ll start, ll end) {
    fill(dp[0], dp[0] + 100001, LLONG_MAX / 2);
    fill(dp[1], dp[1] + 100001, LLONG_MAX / 2);
    fill(visited, visited + 100001, false);
    priority_queue<pair<ll, pll>> pq;
    pq.push({0, {start, 0}});
    dp[0][0] = dp[1][0] = LLONG_MAX / 2;
    while (!pq.empty()) {
        pair<ll, pll> curr = pq.top();
        pq.pop();
        ll c = curr.first;
        pll p = curr.second;
        ll node = p.first, par = p.second;
        if (!visited[node]) {
            visited[node] = true;
            ds[node] = -c;
            dp[0][node] = min(du[node], dp[0][par]);
            dp[1][node] = min(dv[node], dp[1][par]);
            for (auto i : adj[node]) {
                pq.push({c - i.second, {i.first, node}});
            }
        } else if (-c == ds[node]) {
            if (min(du[node], dp[0][par]) + min(dv[node], dp[1][par]) <=
                dp[0][node] + dp[1][node]) {
                dp[0][node] = min(du[node], dp[0][par]);
                dp[1][node] = min(dv[node], dp[1][par]);
            }
        }
    }
    ans = min(ans, dp[0][end] + dp[1][end]);
}

int main() {
    iostream::sync_with_stdio(false);
    cin.tie(0);
    ll n, m, s, t, u, v;
    cin >> n >> m >> s >> t >> u >> v;
    for (int i = 0; i < m; i++) {
        ll a, b, c;
        cin >> a >> b >> c;
        adj[a].push_back({b, c}), adj[b].push_back({a, c});
    }
    dijkstra1(u, du), dijkstra1(v, dv);
    ans = du[v];
    dijkstra2(s, t), dijkstra2(t, s);
    cout << ans << "\n";
    return 0;
}

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