Submission #1362201

#TimeUsernameProblemLanguageResultExecution timeMemory
1362201gayCommuter Pass (JOI18_commuter_pass)C++20
100 / 100
296 ms29828 KiB
#include <bits/stdc++.h>

using namespace std;

using ld = long double;
using ll = long long;

const ll INF = 3e18, MOD = 1e9 + 7;

void solve();

signed main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    int q = 1;
    while (q--) {
        solve();
    }
}

vector<vector<pair<ll, ll>>> g;
ll n;
vector<ll> dist(ll s) {
    vector<ll> ds(n, INF);
    ds[s] = 0;
    set<pair<ll, ll>> dj;
    dj.insert({0, s});
    while (!dj.empty()) {
        ll v = dj.begin()->second;
        dj.erase(dj.begin());
        for (auto [u, c] : g[v]) {
            if (ds[u] > ds[v] + c) {
                dj.erase({ds[u], u});
                ds[u] = ds[v] + c;
                dj.insert({ds[u], u});
            }
        }
    }
    return ds;
}

vector<vector<ll>> g2;
vector<ll> dv, du;
ll ans;
vector<ll> dp1, dp2;

void dfs(ll v) {
    dp1[v] = dv[v]; dp2[v] = du[v];
    for (auto u : g2[v]) {
        if (dp1[u] == -1) {
            dfs(u);
        }
        dp1[v] = min(dp1[v], dp1[u]);
        dp2[v] = min(dp2[v], dp2[u]);
    }
    ans = min({ans, dv[v] + dp2[v], du[v] + dp1[v]});
}

void solve() {
    ll m; cin >> n >> m;
    ll s, t; cin >> s >> t; s--, t--;
    ll u, v; cin >> u >> v; u--, v--;
    g.resize(n);
    for (int i = 0; i < m; i++) {
        ll a, b, c; cin >> a >> b >> c;
        a--, b--;
        g[a].emplace_back(b, c);
        g[b].emplace_back(a, c);
    }
    vector<ll> d1 = dist(s), d2 = dist(t);
    g2.resize(n);
    for (int a = 0; a < n; a++) {
        for (auto [b, c] : g[a]) {
            if (d1[a] + c == d1[b] && d2[b] + c == d2[a]) {
                g2[a].push_back(b);
            }
        }
    }
    dv = dist(v);
    du = dist(u);
    ans = dv[u];
    dp1.resize(n, -1), dp2.resize(n, -1);
    dfs(s);
    cout << ans;
}
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