Submission #626891

#	Time	Username	Problem	Language	Result	Execution time	Memory
626891		colossal_pepe	Robot (JOI21_ho_t4)	C++17	0 / 100	499 ms	49912 KiB

Main

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

const int INF = 1e9;

int n, m;
vector<int> a, b, c, p;
vector<vector<int>> g;
vector<map<int, vector<int>>> h;

int solve() {
    int ans = -INF;
    priority_queue<tuple<int, int, int>> pq;
    int dp[n];
    dp[0] = 0;
    for (int i = 1; i < n; i++) {
        dp[i] = -INF;
    }
    bool vis[n];
    memset(vis, 0, sizeof(vis));
    pq.push({0, 0, m});
    while (not pq.empty()) {
        auto [d, u, c_prev] = pq.top();
        pq.pop();
        if (dp[u] != d) continue;
        //cout << d << ' ' << u << ' ' << c_prev << '\n';
        if (u == n - 1) ans = max(ans, dp[u]);
        if (h[u][c_prev].size() <= 2) {
            for (int e : h[u][c_prev]) {
                int v = b[e];
                if (d <= dp[v]) continue;
                dp[v] = d;
                pq.push({dp[v], v, m});
            }
        }
        if (vis[u]) continue;
        vis[u] = 1;
        for (int e : g[u]) {
            int v = b[e];
            int incur = -(h[u][c[e]].size() > 1);
            if (d + incur <= dp[v]) continue;
            dp[v] = d + incur;
            pq.push({dp[v], v, (incur < 0 ? c[e] : m)});
        }
    }
    return (ans != -INF ? -ans : -1);
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> m;
    m++;
    g.resize(n), h.resize(n);
    a.resize(2 * m), b.resize(2 * m), c.resize(2 * m), p.resize(2 * m);
    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);
        h[a[i]][c[i]].push_back(i);
        h[b[i]][c[i + m]].push_back(i + m);
    }
    cout << solve() << '\n';
    return 0;
}

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