Submission #756381

#	Time	Username	Problem	Language	Result	Execution time	Memory
756381		Kihihihi	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	602 ms	33804 KiB

commuter_pass

#include <iostream>
#include <iomanip>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <cassert>
#include <ctime>
#include <chrono>
#include <cstdio>
#include <random>
#include <vector>
#include <string>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <deque>
#include <queue>
#include <bitset>
#include <list>
#include <fstream>
#include <functional>
#include <complex>
using namespace std;
mt19937_64 rnd(chrono::steady_clock::now().time_since_epoch().count());

const long long INF = 1e18, MOD = 1e9 + 7, MOD2 = 998244353, LOG = 18;
const long double EPS = 1e-9, PI = acos(-1);

struct edge
{
    long long to, w;
};

long long n;
vector<edge> g[100000];
vector<long long> dag[100000], rdag[100000];

void solve()
{
    long long m;
    cin >> n >> m;
    long long s, t, x, y;
    cin >> s >> t >> x >> y;
    s--; t--; x--; y--;
    for (long long i = 0; i < m; i++)
    {
        long long a, b, c;
        cin >> a >> b >> c;
        a--; b--;
        g[a].push_back({ b, c });
        g[b].push_back({ a, c });
    }

    auto dijkstra = [&](long long fr, vector<long long>& dist, bool build) -> void
    {
        dist[fr] = 0;
        set<pair<long long, long long>> q = { { 0, fr } };
        while (q.size())
        {
            auto [d, ver] = *q.begin();
            q.erase(q.begin());
            for (auto& i : g[ver])
            {
                if (d + i.w > dist[i.to])
                {
                    continue;
                }

                if (d + i.w < dist[i.to])
                {
                    q.erase({ dist[i.to], i.to });
                    dist[i.to] = d + i.w;
                    q.insert({ dist[i.to], i.to });

                    if (build)
                    {
                        rdag[i.to] = {};
                    }
                }
                if (d + i.w == dist[i.to] && build)
                {
                    rdag[i.to].push_back(ver);
                }
            }
        }
    };

    vector<long long> frx(n, INF), toy(n, INF), fra(n, INF);
    dijkstra(x, frx, false);
    dijkstra(y, toy, false);
    dijkstra(s, fra, true);
    for (long long i = 0; i < n; i++)
    {
        for (auto& j : rdag[i])
        {
            dag[j].push_back(i);
        }
    }

    vector<bool> used(n);
    vector<long long> mnd(n, INF);

    auto dfs = [&](auto dfs, long long v, long long to)
    {
        used[v] = true;
        if (v == to)
        {
            mnd[v] = toy[v];
            return;
        }

        for (auto& i : dag[v])
        {
            if (!used[i])
            {
                dfs(dfs, i, to);
            }

            mnd[v] = min(mnd[v], mnd[i]);
        }
        if (mnd[v] != INF)
        {
            mnd[v] = min(mnd[v], toy[v]);
        }
    };

    dfs(dfs, s, t);
    long long ans = frx[y];
    for (long long i = 0; i < n; i++)
    {
        if (mnd[i] == INF)
        {
            continue;
        }

        ans = min(ans, frx[i] + mnd[i]);
    }

    used.assign(n, false);
    mnd.assign(n, INF);
    swap(dag, rdag);
    dfs(dfs, t, s);
    for (long long i = 0; i < n; i++)
    {
        if (mnd[i] == INF)
        {
            continue;
        }

        ans = min(ans, frx[i] + mnd[i]);
    }

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

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    srand(time(NULL));

    int tst = 1;
    //cin >> tst;
    while (tst--)
    {
        solve();
    }

    return 0;
}

/*
<3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3
⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⠤⠖⠚⢉⣩⣭⡭⠛⠓⠲⠦⣄⡀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⢀⡴⠋⠁⠀⠀⠊⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠳⢦⡀⠀⠀⠀⠀
⠀⠀⠀⠀⢀⡴⠃⢀⡴⢳⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⣆⠀⠀⠀
⠀⠀⠀⠀⡾⠁⣠⠋⠀⠈⢧⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⢧⠀⠀
⠀⠀⠀⣸⠁⢰⠃⠀⠀⠀⠈⢣⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣇⠀
⠀⠀⠀⡇⠀⡾⡀⠀⠀⠀⠀⣀⣹⣆⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢹⠀
⠀⠀⢸⠃⢀⣇⡈⠀⠀⠀⠀⠀⠀⢀⡑⢄⡀⢀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⡇
⠀⠀⢸⠀⢻⡟⡻⢶⡆⠀⠀⠀⠀⡼⠟⡳⢿⣦⡑⢄⠀⠀⠀⠀⠀⠀⠀⠀⢸⡇
⠀⠀⣸⠀⢸⠃⡇⢀⠇⠀⠀⠀⠀⠀⡼⠀⠀⠈⣿⡗⠂⠀⠀⠀⠀⠀⠀⠀⢸⠁
⠀⠀⡏⠀⣼⠀⢳⠊⠀⠀⠀⠀⠀⠀⠱⣀⣀⠔⣸⠁⠀⠀⠀⠀⠀⠀⠀⢠⡟⠀
⠀⠀⡇⢀⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠠⠀⡇⠀⠀⠀⠀⠀⠀⠀⠀⢸⠃⠀
⠀⢸⠃⠘⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⠁⠀⠀⢀⠀⠀⠀⠀⠀⣾⠀⠀
⠀⣸⠀⠀⠹⡄⠀⠀⠈⠁⠀⠀⠀⠀⠀⠀⠀⡞⠀⠀⠀⠸⠀⠀⠀⠀⠀⡇⠀⠀
⠀⡏⠀⠀⠀⠙⣆⠀⠀⠀⠀⠀⠀⠀⢀⣠⢶⡇⠀⠀⢰⡀⠀⠀⠀⠀⠀⡇⠀⠀
⢰⠇⡄⠀⠀⠀⡿⢣⣀⣀⣀⡤⠴⡞⠉⠀⢸⠀⠀⠀⣿⡇⠀⠀⠀⠀⠀⣧⠀⠀
⣸⠀⡇⠀⠀⠀⠀⠀⠀⠉⠀⠀⠀⢹⠀⠀⢸⠀⠀⢀⣿⠇⠀⠀⠀⠁⠀⢸⠀⠀
⣿⠀⡇⠀⠀⠀⠀⠀⢀⡤⠤⠶⠶⠾⠤⠄⢸⠀⡀⠸⣿⣀⠀⠀⠀⠀⠀⠈⣇⠀
⡇⠀⡇⠀⠀⡀⠀⡴⠋⠀⠀⠀⠀⠀⠀⠀⠸⡌⣵⡀⢳⡇⠀⠀⠀⠀⠀⠀⢹⡀
⡇⠀⠇⠀⠀⡇⡸⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⠮⢧⣀⣻⢂⠀⠀⠀⠀⠀⠀⢧
⣇⠀⢠⠀⠀⢳⠇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⡎⣆⠀⠀⠀⠀⠀⠘
⢻⠀⠈⠰⠀⢸⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠰⠘⢮⣧⡀⠀⠀⠀⠀
⠸⡆⠀⠀⠇⣾⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⠆⠀⠀⠀⠀⠀⠀⠀⠙⠳⣄⡀⢢⡀
<3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3
*/

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