Submission #1005654

#	Time	Username	Problem	Language	Result	Execution time	Memory
1005654		c2zi6	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	264 ms	36144 KiB

commuter_pass

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define replr(i, a, b) for (int i = int(a); i <= int(b); ++i)
#define reprl(i, a, b) for (int i = int(a); i >= int(b); --i)
#define rep(i, n) for (int i = 0; i < int(n); ++i)
#define mkp(a, b) make_pair(a, b)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VPI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<VPI> VVPI;
typedef pair<ll, ll> PLL;
typedef vector<ll> VL;
typedef vector<PLL> VPL;
typedef vector<VL> VVL;
typedef vector<VVL> VVVL;
typedef vector<VPL> VVPL;
template<class T> T setmax(T& a, T b) {if (a < b) return a = b; return a;}
template<class T> T setmin(T& a, T b) {if (a < b) return a; return a = b;}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template<class T>
using indset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

int S, T, U, V;
int n, m;
VVPI gp;

VVI dijkstra(int s, VL& dist, int to = -1) {
    dist = VL(n, 1e18);
    VVI prev(n);
    priority_queue<PLL> pq;
    VI vis(n);
    dist[s] = 0;
    pq.push({0, s});
    while (pq.size()) {
        int u = pq.top().ss;
        pq.pop();
        if (vis[u]) continue;
        vis[u] = true;
        for (auto[v, w] : gp[u]) {
            if (dist[u] + w < dist[v]) {
                prev[v] = VI{u};
                dist[v] = dist[u] + w;
                pq.push({-dist[v], v});
            } else if (dist[u] + w == dist[v]) {
                prev[v].pb(u);
            }
        }
    }
    return prev;
}
VVI trans(VVI gp) {
    int n = gp.size();
    VVI tr(n);
    rep(u, n) for (int v : gp[u]) {
        tr[v].pb(u);
    }
    return tr;
}

void topsort(int u, VVI& gp, VI& vis, VI& order) {
    vis[u] = true;
    for (int v : gp[u]) if (!vis[v]) topsort(v, gp, vis, order);
    order.pb(u);
}
VI topsort(VVI& gp, int u) {
    int n = gp.size();
    VI vis = VI(n);
    VI order;
    topsort(u, gp, vis, order);
    return order;
}

void solve() {
    cin >> n >> m;
    cin >> S >> T >> U >> V;
    S--, T--, U--, V--;
    gp = VVPI(n);
    rep(i, m) {
        int u, v, c;
        cin >> u >> v >> c;
        u--, v--;
        gp[u].pb({v, c});
        gp[v].pb({u, c});
    }
    VL dists, distt, distu, distv;
    VVI prev = dijkstra(S, dists);
    VVI next = trans(prev);
    VI order = topsort(prev, T);
    reverse(all(order));
    dijkstra(T, distt);
    dijkstra(U, distu);
    dijkstra(V, distv);
    ll ans = distu[V];
    VL mindistv, mindistu;
    mindistv = mindistu = VL(n, 1e18);
    for (int x : order) {
        mindistv[x] = distv[x];
        mindistu[x] = distu[x];
        for (int y : next[x]) {
            setmin(mindistv[x], mindistv[y]);
            setmin(mindistu[x], mindistu[y]);
        }
        setmin(ans, distu[x] + mindistv[x]);
        setmin(ans, distv[x] + mindistu[x]);
    }
    cout << ans << endl;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    int t = 1;
    /*cin >> t;*/
    while (t--) solve();
}

Compilation message (stderr)

commuter_pass.cpp: In function 'VVI dijkstra(int, VL&, int)':
commuter_pass.cpp:49:18: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   49 |         for (auto[v, w] : gp[u]) {
      |                  ^

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