Submission #1178275

#	Time	Username	Problem	Language	Result	Execution time	Memory
1178275		biank	Construction Project 2 (JOI24_ho_t2)	C++20	100 / 100	117 ms	23276 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define forn(i,n) for(int i=0;i<int(n);i++)
#define forsn(i,s,n) for(int i=int(s);i<int(n);i++)
#define dforn(i,n) for(int i=int(n)-1;i>=0;i--)
#define dforsn(i,s,n) for(int i=int(n)-1;i>=int(s);i--)
#define fst first
#define snd second
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()

typedef long long ll;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef pair<int,int> ii;

const ll INF=1e18;

vll dijkstra(int s, const vector<vector<ii>> &adj){
    int n=sz(adj);
    vector<ll> dist(n,INF);
    priority_queue<pair<ll,int>> pq;
    pq.emplace(-(dist[s]=0),s);
    while(!pq.empty()){
        auto[d,u]=pq.top(); pq.pop(); d*=-1;
        if(dist[u]!=d) continue;
        for(auto[v,w]:adj[u]) if(dist[v]>dist[u]+w) pq.emplace(-(dist[v]=dist[u]+w),v);
    }
    return dist;
}

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    
    int n,m,s,t; ll l,k;
    cin>>n>>m>>s>>t>>l>>k;
    --s,--t;
    vector<vector<ii>> adj(n);
    forn(i,m){
        int u,v,w;
        cin>>u>>v>>w;
        --u,--v;
        adj[u].eb(v,w);
        adj[v].eb(u,w);
    }
    vll dist_s=dijkstra(s,adj);
    vll dist_t=dijkstra(t,adj);
    if(dist_s[t]<=k){
        cout<<n*(n-1LL)/2<<'\n';
        return 0;
    }
    sort(all(dist_t));
    ll target=k-l;
    ll ans=0;
    auto cnt=[&](ll x){
        return int(upper_bound(all(dist_t),x)-begin(dist_t));
    };
    forn(u,n){
        ans+=cnt(target-dist_s[u]);
    }
    cout<<ans<<'\n';
    
    return 0;
}

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