Submission #1127535

#	Time	Username	Problem	Language	Result	Execution time	Memory
1127535		12345678	Construction Project 2 (JOI24_ho_t2)	C++17	100 / 100	221 ms	25824 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define ll long long

const int nx=2e5+5;

ll n, m, s, t, l, k, u, v, w, a[nx], b[nx], ans, vs[nx];
vector<pair<ll, ll>> d[nx];
priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> pq;
vector<ll> vl;

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n>>m>>s>>t>>l>>k;
    for (int i=1; i<=m; i++) cin>>u>>v>>w, d[u].push_back({v, w}), d[v].push_back({u, w});
    for (int i=1; i<=n; i++) a[i]=b[i]=LLONG_MAX;
    a[s]=b[t]=0;
    pq.push({0, s});
    while (!pq.empty())
    {
        auto [w, u]=pq.top();
        pq.pop();
        if (vs[u]) continue;
        vs[u]=1;
        for (auto [v, nw]:d[u]) if (w+nw<a[v]) a[v]=w+nw, pq.push({w+nw, v});
    }
    if (a[t]<=k) return cout<<(n*(n-1))/2, 0;
    pq.push({0, t});
    for (int i=1; i<=n; i++) vs[i]=0;
    while (!pq.empty())
    {
        auto [w, u]=pq.top();
        pq.pop();
        if (vs[u]) continue;
        vs[u]=1;
        for (auto [v, nw]:d[u]) if (w+nw<b[v]) b[v]=w+nw, pq.push({w+nw, v});
    }
    for (int i=1; i<=n; i++) vl.push_back(b[i]);
    sort(vl.begin(), vl.end());
    for (int i=1; i<=n; i++) if (a[i]!=LLONG_MAX) ans+=(upper_bound(vl.begin(), vl.end(), k-a[i]-l)-vl.begin());
    cout<<ans;
}

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