Submission #979991

#	Time	Username	Problem	Language	Result	Execution time	Memory
979991		vjudge1	Longest Trip (IOI23_longesttrip)	C++17	0 / 100	3074 ms	2416 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector <int>;
using vll = vector <ll>;

const ll MAXN = 256;
vll adj[MAXN];
ll mat[MAXN][MAXN];

// diameter common fishel L
pair <ll, vi> bfs (ll n, ll u) {
    vector <char> vis(n, false);
    vll dis(n), from(n);
    queue <ll> q;
    vis[u] = true;
    dis[u] = 0;
    from[u] = u;
    q.push(u);
    ll far = u;
    while (q.size()) {
        ll u = q.front(); q.pop();
        for (ll v : adj[u]) {
            if (vis[v]) continue;
            vis[v] = true;
            dis[v] = dis[u]+1;
            from[v] = u;
            q.push(v);
            far = v;
        }
    }
    ll ffar = far;
    vi path;
    while (far != from[far]) {
        path.push_back(far);
        far = from[far];
    }
    path.push_back(far);
    return { ffar, path };
}

vi longest_trip (int n, int d) {
    fill(adj, adj+n, vll({}));
    for (ll u = 0; u < n; u++) {
        for (ll v = u+1; v < n; v++) {
            if (are_connected(vi({ int(u) }), vi({ int(v) }))) {
                adj[u].push_back(v);
                adj[v].push_back(u);
                mat[u][v] = true;
                mat[v][u] = true;
            } else {
                mat[u][v] = false;
                mat[v][u] = false;
            }
        }
    }
    vi ans = {};
    for (ll v = 0; v < n; v++) {
        vi pans = {};
        for (ll u = 0; u < n; u++) {
            vi path = bfs(n, bfs(n, 0).first).second;
            if (path.size() > pans.size()) pans = path;
        }
        deque <int> dq(pans.begin(), pans.end());
        ll ex1 = dq.front(), ex2 = dq.back();
        vector <char> vis(n, false);
        for (ll u : dq) vis[u] = true;
        for (ll u = 0; u < n; u++) {
            if (vis[u]) continue;
            if (mat[u][ex1]) {
                dq.push_front(u);
                ex1 = u;
            } else if (mat[u][ex2]) {
                dq.push_back(u);
                ex2 = u;
            }
        }
        pans = vi(dq.begin(), dq.end());
        if (pans.size() > ans.size()) ans = pans;
    }
    return ans;
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 5
• Subtask 2: 0 / 10
• Subtask 3: 0 / 25
• Subtask 4: 0 / 60