Submission #1262199

#	Time	Username	Problem	Language	Result	Execution time	Memory
1262199		tuanmwillwinvoi26	Construction Project 2 (JOI24_ho_t2)	C++20	100 / 100	140 ms	24256 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define el '\n'
#define TASK "metro"
#define int long long

const int INF = 1e18 + 829;
const int MAXN = 2e5 + 5;

int n , m;
int s , t , l , k;
vector <pair<int , int>> adj[MAXN];
int dist_s[MAXN] , dist_t[MAXN];
int res;
vector <int> v;
priority_queue <pair<int , int> , vector<pair<int , int>> , greater<pair<int , int>>> pq;

void dijkstra(int node , int dist[]){
    for(int i = 1 ; i <= n ; i ++){
        dist[i] = INF;
    }

    dist[node] = 0;
    pq.push({0 , node});

    while(! pq.empty()){
        int cost = pq.top().first;
        int u = pq.top().second;
        pq.pop();
        if (cost != dist[u]) continue;
        for(auto x : adj[u]){
            int v = x.first;
            int w = x.second;
            if (dist[v] > dist[u] + w){
                dist[v] = dist[u] + w;
                pq.push({dist[v] , v});
            }
        }
    }

}

signed main(){
    if (fopen(TASK".inp" , "r")){
        freopen(TASK".inp" , "r" , stdin); 
        freopen (TASK".out" , "w" , stdout); 
    }

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> n >> m >> s >> t >> l >> k;

    for(int i = 1 ; i <= m ; i ++){
        int u , v , w;
        cin >> u >> v >> w;
        adj[u].push_back({v , w});
        adj[v].push_back({u , w});
    }

    dijkstra(s , dist_s);

    if (dist_s[t] <= k){
        cout << n * (n - 1) / 2;
        return 0;
    }

    dijkstra(t , dist_t);
    
    for(int i = 1 ; i <= n ; i ++){
        v.push_back(dist_t[i]);
    }

    sort(v.begin() , v.end());

    for(int i = 1 ; i <= n ; i ++){
        if (dist_s[i] == INF) continue;
        int wanted = k - l - dist_s[i];
        if (wanted < 0) continue;
        int pos = upper_bound(v.begin() , v.end() , wanted) - v.begin();
        res += pos;
    }

    cout << res;

    return 0;
}

/*
⠀⠀⠀⠀⠀⠀⢀⡤⣤⣀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⡀
⠀⠀⠀⠀⠀⢀⡏⠀⠀⠈⠳⣄⠀⠀⠀⠀⠀⣀⠴⠋⠉⠉⡆
⠀⠀⠀⠀⠀⢸⠀⠀⠀⠀⠀⠈⠉⠉⠙⠓⠚⠁⠀⠀⠀⠀⣿
⠀⠀⠀⠀⢀⠞⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠹⣄
⠀⠀⠀⠀⡞⠀⠀⠀⠀⠀⠶⠀⠀⠀⠀⠀⠀⠦⠀⠀⠀⠀⠀⠸⡆


                                    */

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:47:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         freopen(TASK".inp" , "r" , stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:48:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |         freopen (TASK".out" , "w" , stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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