Submission #1101006

#	Time	Username	Problem	Language	Result	Execution time	Memory
1101006		anhthi	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	185 ms	16024 KiB

commuter_pass

#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define ll long long
#define mp(x, y) make_pair(x, y)
#define sz(v) ((int) (v).size())
#define all(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define BIT(x, y) (((x) >> (y)) & 1)
#define pb push_back
#define heap priority_queue
#define max_rng *max_element
#define min_rng *min_element
#define rep(i, n) for(int i = 1, _n = (n); i <= _n; ++i)
#define forn(i, a, b) for(int i = (a), _b = (b); i <= _b; ++i)
#define ford(i, a, b) for(int i = (a), _b = (b); i >= _b; --i)

template <class X, class Y>
    inline bool maximize(X &x, Y y) {
        return (x < y ? x = y, true : false);
    }

template <class X, class Y>
    inline bool minimize(X &x, Y y) {
        return (x > y ? x = y, true : false);
    }

template <class X>
    inline void compress(vector<X> &a) {
        sort(all(a));
        a.resize(unique(all(a)) - a.begin());
    }

int ctz(ll x) { return __builtin_ctzll(x); }
int lg(ll x) { return 63 - __builtin_clzll(x); }
int popcount(ll x) { return __builtin_popcount(x); }

const ll oo = (ll) 1e17;
const int INF = (int) 1e9 + 7, MOD = (int) 1e9 + 7;

const int N = 1e5 + 15;

int n, m;
int S, T, U, V;
vector<pair<int, int>> g[N];


ll fu[N], fv[N];
ll f[N], dp[N][2];

void dijkstra(int node, ll f[]) {
    fill(f, f + 1 + n, oo);

    heap<pair<ll, int>> pq;
    pq.push(mp(0, node));
    f[node] = 0;

    while (sz(pq)){
        pair<ll, int> top = pq.top();
        pq.pop();

        int u = top.second;
        ll dist = -top.first;

        if (f[u] != dist) continue;

        for (pair<int, int> i : g[u]) {
            ll nxt = dist + i.second;
            if (minimize(f[i.first], nxt)) {
                pq.push(mp(-nxt, i.first));
            }
        }

    }

    return;
}

int main(void) {
    // think what before starting to code
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    cin >> n >> m;
    cin >> S >> T >> U >> V;

    rep(i, m) {
        int u, v, w;
        cin >> u >> v >> w;
        g[u].pb(mp(v, w));
        g[v].pb(mp(u, w));
    }

    dijkstra(U, fu);
    dijkstra(V, fv);

    ll ans = fu[V];

    memset(f, 0x3f, sizeof f);
    memset(dp, 0x3f, sizeof dp);

    // (dist, u)
    heap<array<ll, 2>> pq;
    pq.push({0, S});

    f[S] = 0;
    dp[S][0] = fu[S]; dp[S][1] = fv[S];

    while (sz(pq)) {
        array<ll, 2> top = pq.top();
        pq.pop();

        int u = top[1];
        ll dist = -top[0];

        if (f[u] != dist) continue;

        // minimize(ans, dp[u][0] + fv[u]);
        // minimize(ans, dp[u][1] + fu[u]);

        // cout << u << ' ' << dist << ' ' << ans << ' ' << dp[u][0] << ' ' << dp[u][1] << '\n';

        for (pair<int, int> i : g[u]) {
            int v = i.first;
            ll new_dist = dist + i.second;

            if (minimize(f[v], new_dist)) {
                dp[v][0] = min(dp[u][0], fu[v]);
                dp[v][1] = min(dp[u][1], fv[v]);
                pq.push({-new_dist, v});
            } 
            else if (f[v] == new_dist) {
                if (min(dp[u][0], fu[v]) + min(dp[u][1], fv[v]) < dp[v][0] + dp[v][1]) {
                    dp[v][0] = min(dp[u][0], fu[v]);
                    dp[v][1] = min(dp[u][1], fv[v]);
                }
            }
        }

    }

    cout << min(ans, dp[T][0] + dp[T][1]);

    return 0;
}

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