Submission #1275024

#	Time	Username	Problem	Language	Result	Execution time	Memory
1275024		hynmj	Construction Project 2 (JOI24_ho_t2)	C++20	100 / 100	250 ms	31756 KiB

Main

#include <bits/stdc++.h>
#define int long long
#define first first
const int N = 2e5 + 7;
using namespace std;
vector<pair<int, int>> graph[N];

vector<int> dijkstra(int start, vector<int> &dist)
{
    set<pair<int, int>> q;
    vector<int> vis(dist.size(), 0);
    q.insert({0, start});
    dist[start] = 0;
    int node, weight;
    while (q.size())
    {
        node = q.begin()->second;
        q.extract(*q.begin());
        if (vis[node])
            continue;
        vis[node] = 1;
        for (auto i : graph[node])
        {
            if (dist[i.second] > dist[node] + i.first)
            {
                dist[i.second] = dist[node] + i.first;
                q.insert({dist[i.second], i.second});
            }
        }
    }
    return dist;
}

void solve()
{
    int n, m;
    cin >> n >> m;
    int s, t, l, k;
    cin >> s >> t >> l >> k;

    int u, v, w;

    for (int i = 0; i < m; i++)
    {
        cin >> u >> v >> w;
        graph[u].push_back({w, v});
        graph[v].push_back({w, u});
    }
    vector<int> sdist(n + 1, 1e18);
    vector<int> tdist(n + 1, 1e18);
    dijkstra(s, sdist);
    dijkstra(t, tdist);
    int ans = 0;
    if (sdist[t] <= k)
    {
        cout << n * (n - 1) / 2;
        return;
    }
    sort(sdist.begin() + 1, sdist.end());
    sort(tdist.begin() + 1, tdist.end());
    for (int i = 1; i <= n; i++)
    {
        if (sdist[i] == 1e18)
            continue;
        int kk = --upper_bound(tdist.begin(), tdist.end(), k - l - sdist[i]) - tdist.begin();
        ans += max(0ll, kk);
    }

    cout << ans << endl;
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    int t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
        cout << endl;
    }
    return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 16 / 16
• Subtask 3: 29 / 29
• Subtask 4: 47 / 47