Submission #631250

#	Time	Username	Problem	Language	Result	Execution time	Memory
631250		colossal_pepe	Olympic Bus (JOI20_ho_t4)	C++17	0 / 100	1086 ms	3384 KiB

ho_t4

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

using ll = long long;

const ll INF = 1e18;

int n, m;
vector<tuple<int, int, ll, ll>> edges;
vector<vector<int>> g;

ll bfs(int start, int flipped) {
    ll dp[n];
    for (int i = 0; i < n; i++) {
        dp[i] = -INF;
    }
    priority_queue<tuple<ll, int>> pq;
    dp[start] = 0;
    pq.push({0, start});
    while (not pq.empty()) {
        auto [dist, u] = pq.top();
        pq.pop();
        if (dp[u] != dist) continue;
        for (int e : g[u]) {
            auto [a, b, c, d] = edges[e];
            if (flipped == e) swap(a, b);
            if (dist - c > dp[b]) {
                dp[b] = dist - c;
                pq.push({dist - c, b});
            }
        }
    }
    return -dp[start ? 0 : n - 1];
}

ll solve(int flipped) {
    return bfs(0, flipped) + bfs(n - 1, flipped) + get<3>(edges[flipped]);
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> m;
    g.resize(m), edges.resize(m + 1);
    auto &[a, b, c, d] = edges[0];
    a = b = -1;
    c = d = 0;
    for (int i = 1; i <= m; i++) {
        auto &[a, b, c, d] = edges[i];
        cin >> a >> b >> c >> d;
        a--, b--;
        g[a].push_back(i);
        g[b].push_back(i);
    }
    ll ans = INF;
    for (int i = 0; i <= m; i++) {
        ans = min(ans, solve(i));
    }
    cout << (ans != INF ? ans : -1) << '\n';
    return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 63