Submission #1253187

#	Time	Username	Problem	Language	Result	Execution time	Memory
1253187		MinhKien	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	242 ms	24120 KiB

commuter_pass

#include <iostream>
#include <vector>
#include <queue>

using namespace std;

#define ll long long
#define li pair <ll, int>
#define fi first
#define se second

const int N = 1e5 + 10;
const ll INF = 1e18;

int n, m, A, B, C, D;
int x, y, w;
bool vis[N];
ll fromA[N], fromB[N], fromC[N], fromD[N];
vector <li> v[N];
priority_queue < li, vector <li>, greater <li> > q;

void dijkstra(int S, ll dis[]) {
    fill_n(dis, n + 1, INF);
    dis[S] = 0;
    q.push(li(0, S));

    while (!q.empty()) {
        int u = q.top().se;
        ll wei = q.top().fi;
        q.pop();

        if (wei > dis[u]) continue;

        for (li z: v[u]) {
            if (wei + z.fi < dis[z.se]) {
                dis[z.se] = wei + z.fi;
                q.push(li(dis[z.se], z.se));
            }
        }
    }
}

ll dp[2][N], best;
void DFS(int s) {
    vis[s] = true;
    dp[0][s] = dp[1][s] = INF;
    for (li z: v[s]) {
        if (fromA[s] + fromB[z.se] + z.fi != fromA[B]) continue;

        if (!vis[z.se]) DFS(z.se);
        dp[0][s] = min(dp[0][s], dp[0][z.se]);
        dp[1][s] = min(dp[1][s], dp[1][z.se]);
    }

    best = min(best, min(dp[0][s] + fromD[s], dp[1][s] + fromC[s]));

    dp[0][s] = min(dp[0][s], fromC[s]);
    dp[1][s] = min(dp[1][s], fromD[s]);
}

int main() {
    cin.tie(0); cout.tie(0);
    ios_base::sync_with_stdio(false);

    cin >> n >> m >> A >> B >> C >> D;
    while (m--) {
        cin >> x >> y >> w;
        v[x].push_back(li(w, y));
        v[y].push_back(li(w, x));
    }

    dijkstra(A, fromA);
    dijkstra(B, fromB);
    dijkstra(C, fromC);
    dijkstra(D, fromD);

    best = fromC[D];
    DFS(A);

    cout << best << "\n";

    return 0;
}

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