Submission #406501

#	Time	Username	Problem	Language	Result	Execution time	Memory
406501		Falcon	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	375 ms	27460 KiB

commuter_pass

#include <bits/stdc++.h>

#ifdef DEBUG
#include "debug.hpp"
#endif

using namespace std;

#define all(c)              (c).begin(), (c).end()
#define rall(c)             (c).rbegin(), (c).rend()
#define traverse(c, it)     for(auto it = (c).begin(); it != (c).end(); ++it)
#define rep(i, N)           for(int i = 0; i < (N); ++i)
#define rrep(i, N)          for(int i = (N) - 1; i >= 0; --i)
#define rep1(i, N)          for(int i = 1; i <= (N); ++i)
#define rep2(i, s, e)       for(int i = (s); i <= (e); ++i)

#ifdef DEBUG
#define debug(x...)         { \
                            ++dbg::depth; \
                            string dbg_vals = dbg::to_string(x); \
                            --dbg::depth; \
                            dbg::fprint(__func__, __LINE__, #x, dbg_vals); \
                            }

#define light_debug(x)      { \
                            dbg::light = true; \
                            dbg::dout << __func__ << ":" << __LINE__; \
                            dbg::dout << "  " << #x << " = " << x << endl; \
                            dbg::light = false; \
                            }

#else
#define debug(x...)         42
#define light_debug(x)      42
#endif


using ll = long long;

template<typename T>
inline T& ckmin(T& a, T b) { return a = a > b ? b : a; }

template<typename T>
inline T& ckmax(T& a, T b) { return a = a < b ? b : a; }


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int N, M, S, T, U, V; cin >> N >> M >> S >> T >> U >> V; --S, --T, --U, --V;
    vector<vector<pair<int, long long>>> adj(N);
    rep(i, M) {
        int u, v; long long w; cin >> u >> v >> w; --u, --v;
        adj[u].push_back({v, w}), adj[v].push_back({u, w});
    }

    auto dijkstra = [&](int s) -> vector<long long> {
        vector<long long> dist(N, -1);
        priority_queue<pair<long long, int>,
                       vector<pair<long long, int>>,
                       greater<pair<long long, int>>> pq;
        pq.push({0, s});
        while(!pq.empty()) {
            auto [d, u] = pq.top(); pq.pop();
            if(~dist[u]) continue;
            dist[u] = d;
            for(auto [v, w]: adj[u])
                if(dist[v] == -1)
                    pq.push({d + w, v});
        }

        return dist;
    };


    vector<long long> dist_u = dijkstra(U), dist_v = dijkstra(V);

    auto dijkstra2 = [&]() -> long long {
        struct dist_t {
            long long d_s, d_u, d_v;
            
            bool operator >(const dist_t& d) const {
                return d_s > d.d_s || (d_s == d.d_s && d_u + d_v > d.d_u + d.d_v);
            }
        }; 

        auto add_edge = [&](dist_t d, int u, int v, long long w) -> dist_t {
            long long m_u = min({dist_u[u], dist_u[v], d.d_u});
            long long m_v = min({dist_v[u], dist_v[v], d.d_v});
            return {d.d_s += w, m_u, m_v};
        };

        auto comp = [](const pair<dist_t, int>& a, const pair<dist_t, int>& b) {
            if(a.first > b.first)
                return true;
            if(b.first > a.first)
                return false;
            return a.second > b.second;            
        };

        vector<dist_t> dist(N);
        vector<bool> vis(N);

        priority_queue<pair<dist_t, int>, 
                       vector<pair<dist_t, int>>,
                       decltype(comp)> pq(comp);

        pq.push({dist_t{0, dist_u[S], dist_v[S]}, S});
        while(!pq.empty()) {
            auto [d, u] = pq.top(); pq.pop();
            if(vis[u]) continue;
            vis[u] = true;
            dist[u] = d;
            for(auto [v, w]: adj[u])
                if(!vis[v])
                    pq.push({add_edge(d, u, v, w), v});
        }

        return dist[T].d_u + dist[T].d_v;
    };


    cout << min(dijkstra2(), dist_u[V]) << '\n';
    
    
    #ifdef DEBUG
    dbg::dout << "\nExecution time: "
              << clock() * 1000 / CLOCKS_PER_SEC 
              << "ms" << endl;
    #endif
    return 0;
}

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