Submission #1089834

#	Time	Username	Problem	Language	Result	Execution time	Memory
1089834		MinhKien	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	202 ms	28592 KiB

commuter_pass

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

using namespace std;

#define ll long long
#define li pair <ll, int>
const int N = 1e5 + 10;

int n, m, x, y;
int a, b, c, d;
ll cost, A[N], B[N], C[N], D[N];
vector <li> v[N];

void dijkstra(int st, ll dis[]) {
    fill_n(dis, n + 1, 1e17);
    dis[st] = 0;

    priority_queue < li, vector <li>, greater <li> > q;
    q.push(li(0, st));

    while (!q.empty()) {
        li p = q.top(); q.pop();
        int u = p.second;
        ll w = p.first;

        if (w > dis[u]) continue;

        for (li z: v[u]) {
            if (z.first + w < dis[z.second]) {
                dis[z.second] = z.first + w;
                q.push(li(dis[z.second], z.second));
            }
        }
    }
}

void pre() {
    dijkstra(a, A);
    dijkstra(b, B);
    dijkstra(c, C);
    dijkstra(d, D);
}

ll best = 1e17;
ll dp[2][N];
bool vis[N];
void dfs(int s, int p) {
    vis[s] = true;
    dp[0][s] = dp[1][s] = 1e17;

    for (li z: v[s]) {
        if (A[s] + z.first + B[z.second] == A[b]) {
            if (z.second == p) continue;

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

    best = min(best, dp[0][s] + C[s]);
    best = min(best, dp[1][s] + D[s]);

    dp[0][s] = min(dp[0][s], D[s]);
    dp[1][s] = min(dp[1][s], C[s]);
}

void solve() {
    best = C[d];
    dfs(a, -1);

    cout << best << "\n";
}

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

    cin >> n >> m;
    cin >> a >> b >> c >> d;
    while (m--) {
        cin >> x >> y >> cost;
        v[x].push_back(li(cost, y));
        v[y].push_back(li(cost, x));
    }

    pre();
    solve();

    return 0;
}

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