Submission #679406

#	Time	Username	Problem	Language	Result	Execution time	Memory
679406		kusssso	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	402 ms	29456 KiB

commuter_pass

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
const int N = 1e5 + 5;
const ll inf = 1e18;
typedef pair<int, ll> edge;
#define fi first
#define se second

struct Node {
    ll fu;
    int u;
    bool hu, hv;
    bool operator < (const Node& oth) const {
        return fu > oth.fu;
    }  
};

int n, m;
int S, T, U, V;
ll f[N][2][2], ans;
vector<edge> g[N];
vector<int> pa[N];
vector<ll> du, dv, ds, dt;

vector<ll> Dij (int st) {
    for (int i = 1; i <= n; i++) pa[i].clear();
    vector<ll> d(n + 1, inf);
    d[st] = 0;
    priority_queue<pair<ll, int>> pq;
    pq.push({0, st});
    while (!pq.empty()) {
        ll du = -pq.top().fi;
        int u = pq.top().se;
        pq.pop();
        if (d[u] != du) continue;
        for (auto e : g[u]) {
            int v = e.fi;
            ll w = e.se;
            if (d[v] > d[u] + w) {
                d[v] = d[u] + w;
                pq.push({-d[v], v});
                pa[v] = {u};
            }
            else if (d[v] == d[u] + w) {
                pa[v].push_back(u);
            }
        }
    }
    return d;
}

ll dp1[N], dp2[N];
bool vis[N];

void dfs (int i) {
    vis[i] = 1;
    dp1[i] = min(dp1[i], du[i]);
    dp2[i] = min(dp2[i], dv[i]);
    for (auto &j : pa[i]) {
        if (!vis[j]) dfs(j);
        dp1[i] = min(dp1[i], dp1[j]);
        dp2[i] = min(dp2[i], dp2[j]);
    }
    ans = min(ans, dp1[i] + dv[i]);
    ans = min(ans, dp2[i] + du[i]);
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    cin >> n >> m >> S >> T >> U >> V;
    for (int i = 0; i < m; i++) {
        int u, v, c;
        cin >> u >> v >> c;
        g[u].push_back({v, c});
        g[v].push_back({u, c});
    }
    du = Dij(U);
    dv = Dij(V);
    dt = Dij(T);
    ds = Dij(S);
    
    ans = du[V];
    
    fill(begin(dp1), end(dp1), inf);
    fill(begin(dp2), end(dp2), inf);
    dfs(T);
    cout << ans;
    
    return 0;
}

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