Submission #626759

#	Time	Username	Problem	Language	Result	Execution time	Memory
626759		colossal_pepe	Robot (JOI21_ho_t4)	C++17	34 / 100	413 ms	12060 KiB

Main

#include <iostream>
#include <vector>
#include <queue>
#include <map>
using namespace std;

using ll = long long;

const ll INF = 1e18;

int n, m, a[200005], b[200005], c[200005];
ll p[200005];
vector<vector<int>> g;

ll solve() {
    priority_queue<tuple<ll, int, bool>> pq;
    ll dp[2 * m][2];
    for (int i = 0; i < 2 * m; i++) {
        dp[i][0] = dp[i][1] = -INF;
    }
    dp[m - 1][0] = 0;
    pq.push({0, m - 1, 0});
    while (not pq.empty()) {
        auto [d, e_prev, changed] = pq.top();
        pq.pop();
        if (dp[e_prev][changed] != d) continue;
        int u = b[e_prev];
        // cout << "! " << d << ' ' << e_prev << ' ' <<  u << '\n';
        map<int, ll> cost;
        if (changed) cost[c[e_prev]] -= p[e_prev];
        for (int e_nxt : g[u]) {
            cost[c[e_nxt]] += p[e_nxt];
        }
        for (int e_nxt : g[u]) {
            ll incur = min(0ll, cost[c[e_nxt]] - p[e_nxt]);
            if (d + incur > dp[e_nxt][0]) {
                dp[e_nxt][0] = d + incur;
                pq.push({dp[e_nxt][0], e_nxt, 0});
            }
            incur = p[e_nxt];
            if (d + incur > dp[e_nxt][1]) {
                dp[e_nxt][1] = d + incur;
                pq.push({dp[e_nxt][1], e_nxt, 1});
            }
        }
    }
    ll ans = -INF;
    for (int i = 0; i < 2 * m; i++) {
        if (b[i] == n - 1) {
            // cout << -dp[i][0] << ' ' << -dp[i][1] << '\n';
            ans = max(ans, max(dp[i][0], dp[i][1]));
        }
    }
    return (ans != -INF ? -ans : -1);
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> m;
    m++;
    g.resize(n);
    for (int i = 0; i < m - 1; i++) {
        cin >> a[i] >> b[i] >> c[i] >> p[i];
        a[i]--, b[i]--;
        p[i] *= -1;
        a[i + m] = b[i];
        b[i + m] = a[i];
        c[i + m] = c[i];
        p[i + m] = p[i];
        g[a[i]].push_back(i);
        g[b[i]].push_back(i + m);
    }
    cout << solve() << '\n';
    return 0;
}

• Subtask 1: 34 / 34
• Subtask 2: 0 / 24
• Subtask 3: 0 / 42