Submission #793541

#	Time	Username	Problem	Language	Result	Execution time	Memory
793541		kebine	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	270 ms	25568 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define ld long double
#define fi first
#define se second

int a[4];
bool vis[100005];
ll dist[4][100005], b[4][100005];
vector<pair<int, ll>> adj[100005];
priority_queue<pair<ll, int>> pq;

void bfs(int type) {
    pq.push({0, a[type]});
    while (!pq.empty()) {
        int x = pq.top().se;
        ll d = -pq.top().fi;
        pq.pop();
        if (dist[type][x] != d) continue;
        for (auto u : adj[x]) if (d + u.se < dist[type][u.fi]) dist[type][u.fi] = d + u.se, pq.push({-(d + u.se), u.fi}); 
    }
}

int main() { 
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < 4; i++) cin >> a[i];
    for (int i = 0; i < 4; i++) {
        for (int j = 1; j <= n; j++) {
            if (j != a[i]) dist[i][j] = 1e18;
            b[i][j] = 1e18;
        }
    }
    for (int i = 0; i < m; i++) {
        int x, y;
        ll w;
        cin >> x >> y >> w;
        adj[x].push_back({y, w});
        adj[y].push_back({x, w});
    }
    for (int i = 0; i < 4; i++) bfs(i);
    ll ans = dist[2][a[3]];
    b[0][a[0]] = dist[0][a[2]], b[1][a[0]] = dist[0][a[3]], b[2][a[0]] = dist[0][a[2]], b[3][a[0]] = dist[0][a[3]];
    vis[a[0]] = 1;
    pq.push({0, a[0]});
    while (!pq.empty()) {
        int x = pq.top().se;
        pq.pop();
        ans = min(ans, min(b[0][x] + b[1][x], b[2][x] + b[3][x]));
        for (auto u : adj[x]) {
            if (dist[0][x] + u.se + dist[1][u.fi] != dist[0][a[1]]) continue;
            ll t1 = min(b[0][x], dist[2][u.fi]), t2 = min(b[1][x], dist[3][u.fi]), t3 = min(b[2][x], dist[2][u.fi]), t4 = min(b[3][x], dist[3][u.fi]);
            if (b[0][u.fi] > t1) b[0][u.fi] = t1, b[1][u.fi] = t2;
            else if (b[0][u.fi] == t1) b[1][u.fi] = min(b[1][u.fi], t2);
            if (b[3][u.fi] > t4) b[2][u.fi] = t3, b[3][u.fi] = t4;
            else if (b[3][u.fi] == t4) b[2][u.fi] = min(b[2][u.fi], t3);
            if (!vis[u.fi]) pq.push({-dist[0][u.fi], u.fi}); 
            vis[u.fi] = 1;
        }
    }
    cout << ans << "\n";
} 

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