Submission #685340

#	Time	Username	Problem	Language	Result	Execution time	Memory
685340		saayan007	Commuter Pass (JOI18_commuter_pass)	C++17	31 / 100	191 ms	20204 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using pi = pair<int, int>;
using pl = pair<long long, long long>;
using vi = vector<int>;
using vl = vector<long long>;
using vpi = vector<pair<int, int>>;
using vpl = vector<pair<long long, long long>>;

#define fur(i, a, b) for(ll i = a; i <= (ll)b; ++i)
#define ruf(i, a, b) for(ll i = a; i >= (ll)b; --i)
#define fr first 
#define sc second
#define mp make_pair
#define pb emplace_back
#define nl "\n"
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()

const ll mxn = 1e5L + 1;
const ll inf = 1e16L;
ll n, m, s, t, u, v;
vpl adj[mxn];

int main() 
{
    ios::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m >> s >> t >> u >> v;
    fur(i, 1, m) {
        ll a, b, c;
        cin >> a >> b >> c;
        adj[a].pb(b, c);
        adj[b].pb(a, c);
    }

    priority_queue<pl> pq;
    ll dist[n + 1];
    fur(i, 1, n) {
        dist[i] = inf;
    }

    ll from[n + 1] = {};
    dist[s] = 0;
    pq.emplace(-dist[s], s);
    // finding shortest route(s) to t
    while(!pq.empty()) {
        ll a = pq.top().sc;
        if(dist[a] + pq.top().fr != 0) {
            pq.pop();
            continue;
        }
        pq.pop();

        for(auto [b, c] : adj[a]) {
            if(dist[b] > dist[a] + c) {
                dist[b] = dist[a] + c;
                pq.emplace(-dist[b], b);
                from[b] = a;
            }
        }
    }

    // nodes on the shortest route(s)
    bool zer[n + 1] = {};
    pq.emplace(dist[t], t);
    while(!pq.empty()) {
        ll a = pq.top().sc;
        pq.pop();
        if(zer[a])
            continue;
        zer[a] = 1;

        for(auto [b, c] : adj[a]) {
            if(dist[a] - c == dist[b]) {
                pq.emplace(dist[b], b);
            }
        }
    }


    // shortest path from u to a zero node as well as to v
    fur(i, 1, n) {
        dist[i] = inf;
    }
    dist[u] = 0;
    pq.emplace(-dist[u], u);
    ll to_zer = inf;
    while(!pq.empty()) {
        ll a = pq.top().sc;
        if(dist[a] + pq.top().fr != 0) {
            pq.pop();
            continue;
        }
        pq.pop();
        if(zer[a]) {
            to_zer = min(to_zer, dist[a]);
        }

        for(auto [b, c] : adj[a]) {
            if(zer[a] && zer[b]) {
                c = 0;
            }
            if(dist[a] + c < dist[b]) {
                dist[b] = dist[a] + c;
                pq.emplace(-dist[b], b);
            }
        }
    }

    // cout << to_zer << nl;
    // fur(i, 1, n) {
        // cout << dist[i] << ' ';
    // }
    // cout << nl;

    cout << dist[v] << nl;
}

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45