Submission #1057501

#	Time	Username	Problem	Language	Result	Execution time	Memory
1057501		sammyuri	Construction Project 2 (JOI24_ho_t2)	C++17	100 / 100	352 ms	42648 KiB

Main

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;

typedef long long ll;
typedef tree<pair<ll, int>, null_type, less<pair<ll, int>>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

const int MAXN = 2e5 + 5;

const ll INF = 1e18;
int n;
vector<pair<int, ll>> adj[MAXN];

void dijkstra(int startnode, vector<ll> &dist) {
    dist.clear(); dist.resize(n, INF);
    dist[startnode] = 0;
    priority_queue<pair<ll, int>> pq;
    pq.push({0, startnode});
    while (pq.size()) {
        pair<ll, int> cur = pq.top(); pq.pop();
        ll curdist = -cur.first;
        int curnode = cur.second;
        if (dist[curnode] != curdist)
            continue;
        for (auto a : adj[curnode]) {
            ll newdist = curdist + a.second;
            if (dist[a.first] > newdist) {
                dist[a.first] = newdist;
                pq.push({-newdist, a.first});
            }
        }
    }
}

int main() {
    int m; cin >> n >> m;
    int s, t; ll l, k; cin >> s >> t >> l >> k;
    s --; t --;
    while (m --) {
        int a, b; ll c; cin >> a >> b >> c;
        a --; b --;
        adj[a].push_back({b, c});
        adj[b].push_back({a, c});
    }
    vector<ll> dist_forwards, dist_backwards;
    dijkstra(s, dist_forwards);
    dijkstra(t, dist_backwards);
    if (dist_forwards[t] <= k) {
        cout << (ll)(n * (ll)(n - 1)) / 2; return 0;
    }
    ll ans = 0;
    ordered_set vals;
    for (int i = 0; i < n; i ++)
        vals.insert({dist_backwards[i], i});
    vector<pair<ll, int>> ee;
    for (int i = 0; i < n; i ++)
        ee.push_back({dist_forwards[i], i});
    sort(ee.begin(), ee.end());
    for (int ii = 0; ii < n; ii ++) {
        int i = ee[ii].second;
        vals.erase({dist_backwards[i], i});
        ll sofar = dist_forwards[i] + l;
        ll req = k - sofar;
        // cout << dist_backwards[i] << " " << sofar << " " <<  vals.order_of_key({req, 1e9}) << endl;
        ll cur = vals.order_of_key({req, 1e9});
        ans += cur;
    }
    cout << ans << endl;
    return 0;
}

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