Submission #1203719

#	Time	Username	Problem	Language	Result	Execution time	Memory
1203719		andrejikus	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	248 ms	18164 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) { cerr << to_string(h); if(sizeof...(t)) cerr << ", "; DBG(t...); }
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)

const int N = 1e5 + 3;
const ll inf = 1e18;
vector<pair<int, int>> adj[N];
bool vis[N];
int n;
ll dis[N][3], dp[N][2], ans = inf;

void Dijkstra(int tp, int u) {
    for (int i = 1; i <= n; i++) dis[i][tp] = inf;
    priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<>> pq;
    pq.emplace(0, u);
    dis[u][tp] = 0;
    while (!pq.empty()) {
        auto [w, c] = pq.top(); pq.pop();
        if (w > dis[c][tp]) continue;
        //dbg(dis[c][tp], c, tp, u);

        for (auto [v, ww] : adj[c]) {
            if (dis[v][tp] <= w+ww) continue;
            dis[v][tp] = w+ww;
            pq.emplace(dis[v][tp], v);
        }
    }
}

void dfs(int u) {
    if (vis[u]) return;
    vis[u] = true;
    dp[u][0] = dis[u][1];
    dp[u][1] = dis[u][2];

    for (auto [x, w] : adj[u]) {
        if (dis[x][0]+w != dis[u][0]) continue;
        dfs(x);
        dp[u][0] = min(dp[u][0], dp[x][0]);
        dp[u][1] = min(dp[u][1], dp[x][1]);
    }
    ans = min(ans, dp[u][0] + dis[u][2]);
    ans = min(ans, dp[u][1] + dis[u][1]);
}

void solve() {
    int m; cin >> n >> m;
    int s, t; cin >> s >> t;
    int u, v; cin >> u >> v;
    for (int i = 0; i < m; i++) {
        int u, v, c; cin >> u >> v >> c;
        adj[u].push_back({v, c});
        adj[v].push_back({u, c});
    }
    Dijkstra(0, s);
    Dijkstra(1, u);
    Dijkstra(2, v);
    ans = dis[u][2];
    dfs(t);

    cout << ans << "\n";
}

signed main() {
    ios::sync_with_stdio(false); cin.tie(0);
	int t=1; //cin >> t;
	while (t--) {
        solve();
	}
}

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