Submission #891717

#	Time	Username	Problem	Language	Result	Execution time	Memory
891717		Mr_Ell	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	301 ms	35836 KiB

commuter_pass

#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const ll INF = 1e18, MOD = 1e9 + 7, P = 239;
const ld PI = 3.1415926535897938462643383279502, EPS = 1e-7;

template <typename T>
inline ll sz(const T &a) {
    return a.size();
}

template <typename T, typename C>
istream &operator >> (istream &in, pair<T, C> &a) {
    return in >> a.first >> a.second;
}

template <typename T, typename C>
ostream &operator << (ostream &out, pair<T, C> a) {
    return out << a.first << ' ' << a.second;
}

template <typename T>
istream & operator >> (istream &in, vector<T> &a) {
    for (auto &i : a) {
        in >> i;
    }
    return in;
}

template <typename T>
ostream &operator << (ostream &out, vector<T> a) {
    for (auto i : a) {
        out << i << ' ';
    }
    return out;
}

template <typename T>
void prnt(vector<T> a, string c = "\n") {
    for (T i : a) {
        cout << i << c;
    }
}

const ll MAXN = 2e5 + 1;
vector<pair<ll, ll>> g[MAXN];
ll dp[MAXN][2];

void dijkstra(vector<ll> &d, ll start) {
    fill(d.begin(), d.end(), INF);
    set<pair<ll, ll>> q;
    q.insert({0, start});
    d[start] = 0;
    while (!q.empty()) {
        auto [dist, v] = *q.begin();
        q.erase(q.begin());
        if (dist > d[v]) {
            continue;
        }
        for (auto [u, w] : g[v]) {
            if (d[u] > d[v] + w) {
                d[u] = d[v] + w;
                q.insert({d[u], u});
            }
        }
    }
}

vector<ll> g2[MAXN], order;
bitset<MAXN> used, good;
vector<ll> du, dv;

void dfs(ll v) {
    used[v] = 1;
    dp[v][0] = du[v];
    dp[v][1] = dv[v];
    for (auto u : g2[v]) {
        if (!used[u]) {
            dfs(u);
        }
        dp[v][0] = min(dp[u][0], dp[v][0]);
        dp[v][1] = min(dp[u][1], dp[v][1]);
    }
    order.push_back(v);
}

void solve() {
    ll n, m, s, t, u, v;
    cin >> n >> m >> s >> t >> u >> v;
    for (ll i = 0; i < m; ++i) {
        ll a, b, w;
        cin >> a >> b >> w;
        g[a].push_back({b, w});
        g[b].push_back({a, w});
    }
    vector<ll> ds(n + 1), dt(n + 1);
    du.resize(n + 1);
    dv.resize(n + 1);
    dijkstra(du, u);
    dijkstra(dv, v);
    dijkstra(ds, s);
    dijkstra(dt, t);

    for (ll i = 1; i <= n; ++i) {
        if (ds[i] + dt[i] == ds[t]) {
            good[i] = 1;
        }
    }
    for (ll i = 1; i <= n; ++i) {
        if (!good[i]) {
            continue;
        }
        for (auto [j, w] : g[i]) {
            if (good[j] && ds[i] + w + dt[j] == ds[t]) {
                g2[i].push_back(j);
            }
        }
    }
    fill(dp[0], dp[0] + MAXN * 2, INF);
    dfs(s);
//    std::reverse(order.begin(), order.end());
//
//    dp[s][0] = ds[u];
//    dp[s][1] = ds[v];
//    for (auto i : order) {
//        for (auto j : g2[i]) {
//            dp[j][0] = min(dp[i][0], du[j]);
//            dp[j][1] = min(dp[i][1], dv[j]);
//        }
//    }
    ll ans = dv[u];
    for (ll i = 1; i <= n; ++i) {
        ans = min(ans, min(dp[i][0] + dv[i], dp[i][1] + du[i]));
    }
    cout << ans;
}

signed main() {
#ifdef LOCAL
    freopen("inp.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    freopen("err.txt", "w", stderr);

    auto start_time = clock();
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    ll times = 1;
//    cin >> times;
    while (times--)
        solve(), cout << '\n';

#ifdef LOCAL
    auto end_time = clock();
    cerr << setprecision(3) << fixed << "Execution time: " << (end_time - start_time) * (ll) 1e3 / CLOCKS_PER_SEC << " ms\n";
#endif
    return 0;
}

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