Submission #286654

#	Time	Username	Problem	Language	Result	Execution time	Memory
286654		valerikk	Olympic Bus (JOI20_ho_t4)	C++17	0 / 100	294 ms	2808 KiB

ho_t4

#include <bits/stdc++.h>
using namespace std;

const int N = 205, M = 5e4 + 7;
const int INF = 1e9 + 19;
const long long LINF = 1e18 + 239;
struct Edge {
    int v, u, c, d;

    Edge() {}
    Edge(int v, int u, int c, int d) : v(v), u(u), c(c), d(d) {}
};

int n, m;
Edge edg[M];
vector <int> find_dist(int s, bool rev, int p[N], vector <int> g[N], int ign = -1) {
    vector <int> d(n, INF);
    for (int i = 0; i < n; ++i)
        p[i] = -1;
    priority_queue <pair <int, int>, vector <pair <int, int> >, greater <pair <int, int> > > q;
    d[s] = 0;
    q.push({0, s});
    while (!q.empty()) {
        auto cur = q.top();
        q.pop();
        int v = cur.second;
        if (d[v] != cur.first)
            continue;
        for (auto id : g[v]) {
            if (id == ign)
                continue;
            int w = edg[id].c, u = rev ? edg[id].v : edg[id].u;
            if (d[v] + w < d[u]) {
                d[u] = d[v] + w;
                p[u] = id;
                q.push({d[u], u});
            }
        }
    }
    return d;
}

vector <int> g[N], gr[N];
int p1[N], pn[N];
int rev_p1[N], rev_pn[N];
bool bad1[M], badn[M];
bool rev_bad1[M], rev_badn[M];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        cin >> edg[i].v >> edg[i].u >> edg[i].c >> edg[i].d;
        edg[i].v--;
        edg[i].u--;
        g[edg[i].v].push_back(i);
        gr[edg[i].u].push_back(i);
    }
    auto d1 = find_dist(0, 0, p1, g);
    auto dn = find_dist(n - 1, 0, pn, g);
    auto rev_d1 = find_dist(0, 1, rev_p1, gr);
    auto rev_dn = find_dist(n - 1, 1, rev_pn, gr);
    for (int i = 0; i < n; ++i) {
        if (~p1[i])
            bad1[p1[i]] = 1;
        if (~pn[i])
            badn[pn[i]] = 1;
        if (~rev_p1[i])
            rev_bad1[rev_p1[i]] = 1;
        if (~rev_pn[i])
            rev_badn[rev_pn[i]] = 1;
    }
    long long ans = LINF;
    if (d1[n - 1] != INF && dn[0] != INF)
        ans = (long long)d1[n - 1] + dn[0];
    for (int i = 0; i < m; ++i) {
        vector <int> cur_d1 = bad1[i] ? find_dist(0, 0, p1, g, i) : d1;
        vector <int> cur_dn = badn[i] ? find_dist(n - 1, 0, pn, g, i) : dn;
        vector <int> kek_d1 = rev_bad1[i] ? find_dist(0, 1, rev_p1, gr, i) : rev_d1;
        vector <int> kek_dn = rev_badn[i] ? find_dist(n - 1, 1, rev_pn, gr, i) : rev_dn;
        long long dist1 = cur_d1[n - 1] == INF ? LINF : cur_d1[n - 1], distn = cur_dn[0] == INF ? LINF : cur_dn[0];
        if (cur_d1[edg[i].u] != INF && kek_dn[edg[i].v] != INF)
            dist1 = min(dist1, (long long)edg[i].c + cur_d1[edg[i].u] + kek_dn[edg[i].v]);
        if (cur_dn[edg[i].u] != INF && kek_d1[edg[i].v] != INF)
            distn = min(distn, (long long)edg[i].c + cur_dn[edg[i].u] + kek_d1[edg[i].v]);
        if (dist1 != LINF && distn != LINF)
            ans = min(ans, dist1 + distn + edg[i].d);
    }
    cout << ans;
    return 0;
}

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