Submission #1212006

#	Time	Username	Problem	Language	Result	Execution time	Memory
1212006		trimkus	Longest Trip (IOI23_longesttrip)	C++20	15 / 100	482 ms	740 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>

using namespace std;
int N;

void find_longest(int i, vector<int> adj[], vector<int>& res) {
    vector<int> p(N, -1), mx(N, -1);
    vector<int> dist(N, -1);
    queue<int> q;
    q.push(i);
    p[i] = -2;
    dist[i] = 0;
    while (q.size()) {
        int layer = q.size();
        vector<int> toadd;
        while (layer--) {
            int v = q.front();
            q.pop();
            for (auto& u : adj[v]) {
                if (p[u] == -1) {
                    if (dist[u] < dist[v] + 1) {
                        dist[u] = dist[v] + 1;
                        mx[u] = v;
                        toadd.push_back(u);
                    }
                }
            }
        }
        for (auto& u : toadd) {
            q.push(u);
            p[u] = mx[u];
        }
    }
    int j = i;
    for (int k = 0; k < N; ++k) {
        if (dist[k] > dist[j]) {
            j = k;
        }
    }
    vector<int> now{j};
    vector<bool> vis(N);
    vis[j] = 1;
    while (true) {
        bool ok = false;
        for (auto& u : adj[now.back()]) {
            if (!vis[u]) {
                vis[u] = true;
                now.push_back(u);
                ok = true;
                break;
            }
        }
        if (!ok) break;
    }
    if (now.size() > res.size()) res = now;
}




std::vector<int> longest_trip(int _N, int D)
{
    N = _N;
    vector<int> adj[N];
    for (int i = 0; i < N; ++i) {
        for (int j = i + 1; j < N; ++j) {
            if (are_connected({i}, {j})) {
                adj[i].push_back(j);
                adj[j].push_back(i);
            }
        }
    } 
    // for (int i = 0; i < N; ++i) {
    //     cout << i << " : ";
    //     for (auto& u : adj[i]) {
    //         cout << u << " ";
    //     }
    //     cout << "\n";
    // }
    // cout << "\n";
    vector<int> res;
    for (int i = 0; i < N; ++i) {
        find_longest(i, adj, res);
    }
    return res;
}

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