Submission #1257167

#	Time	Username	Problem	Language	Result	Execution time	Memory
1257167		chikien2009	Olympic Bus (JOI20_ho_t4)	C++20	100 / 100	500 ms	2660 KiB

ho_t4

#include <bits/stdc++.h>

using namespace std;

void setup()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int n, m, a[50000], b[50000], c[50001], d[50000];
bool check[200], onpath[50000];
long long to_0[200], from_0[200], to_n[200], from_n[200], head, tail;
vector<pair<int, int>> g[200], h[200];
long long res = 1e18;
priority_queue<pair<long long, int>> pq;

inline void Dijkstra(int source,
                     vector<pair<int, int>> (&graph)[200],
                     long long (&dist)[200])
{
    int node;
    long long cur;
    fill_n(dist, 200, 1e18);
    dist[source] = 0;
    pq.push({0, source});
    while (!pq.empty())
    {
        cur = -pq.top().first;
        node = pq.top().second;
        pq.pop();
        if (dist[node] != cur)
        {
            continue;
        }
        for (auto &i : graph[node])
        {
            if (dist[i.first] > dist[node] + c[i.second])
            {
                dist[i.first] = dist[node] + c[i.second];
                pq.push({-dist[i.first], i.first});
            }
        }
    }
}

inline void DFS(int node,
                vector<pair<int, int>> (&graph)[200],
                long long (&dist)[200])
{
    check[node] = true;
    for (auto &i : graph[node])
    {
        if (!check[i.first] && dist[node] + c[i.second] == dist[i.first])
        {
            onpath[i.second] = true;
            DFS(i.first, graph, dist);
        }
    }
}

inline long long Check(int block)
{
    int node;
    long long ret = 0, cur, dist[200];
    fill_n(dist, n, 1e18);
    dist[0] = 0;
    pq.push({0, 0});
    while (!pq.empty())
    {
        node = pq.top().second;
        cur = -pq.top().first;
        pq.pop();
        if (cur != dist[node])
        {
            continue;
        }
        for (auto &i : g[node])
        {
            if (i.second != block && dist[i.first] > dist[node] + c[i.second])
            {
                dist[i.first] = dist[node] + c[i.second];
                pq.push({-dist[i.first], i.first});
            }
        }
    }
    ret += dist[n - 1];
    fill_n(dist, n, 1e18);
    dist[n - 1] = 0;
    pq.push({0, n - 1});
    while (!pq.empty())
    {
        node = pq.top().second;
        cur = -pq.top().first;
        pq.pop();
        if (cur != dist[node])
        {
            continue;
        }
        for (auto &i : g[node])
        {
            if (i.second != block && dist[i.first] > dist[node] + c[i.second])
            {
                dist[i.first] = dist[node] + c[i.second];
                pq.push({-dist[i.first], i.first});
            }
        }
    }
    ret += dist[0];
    return ret;
}

int main()
{
    setup();

    cin >> n >> m;
    for (int i = 0; i < m; ++i)
    {
        cin >> a[i] >> b[i] >> c[i] >> d[i];
        a[i]--;
        b[i]--;
        g[a[i]].push_back({b[i], i});
        h[b[i]].push_back({a[i], i});
    }
    Dijkstra(0, g, from_0);
    Dijkstra(0, h, to_0);
    Dijkstra(n - 1, g, from_n);
    Dijkstra(n - 1, h, to_n);
    res = min(res, from_0[n - 1] + from_n[0]);
    DFS(0, g, from_0);
    fill_n(check, 200, 0);
    DFS(n - 1, g, from_n);
    for (int i = 0; i < m; ++i)
    {
        if (onpath[i])
        {
            c[m] = c[i];
            g[b[i]].push_back({a[i], m});
            res = min(res, Check(i) + d[i]);
            g[b[i]].pop_back();
        }
        else
        {
            head = min(from_0[n - 1], from_0[b[i]] + to_n[a[i]] + c[i]);
            tail = min(from_n[0], from_n[b[i]] + to_0[a[i]] + c[i]);
            res = min(res, head + tail + d[i]);
        }
    }
    cout << (res == 1e18 ? -1 : res);
    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 63 / 63