Submission #1049217

#	Time	Username	Problem	Language	Result	Execution time	Memory
1049217		Zicrus	Longest Trip (IOI23_longesttrip)	C++17	5 / 100	732 ms	2208 KiB

longesttrip

#include <bits/stdc++.h>
#include "longesttrip.h"
using namespace std;
 
typedef long long ll;
 
vector<vector<ll>> adj;
vector<bool> vst;
mt19937 mt;
ll sz;

vector<int> mxRand(ll start) {
    ll n = adj.size();
    ll cur = start;
    vector<int> res = {(int)start};
loop:
    vst[cur] = true;
    shuffle(adj[cur].begin(), adj[cur].end(), mt);
    for (auto &e : adj[cur]) {
        if (!vst[e]) {
            cur = e;
            res.push_back(e);
            goto loop;
        }
    }
    for (auto &e : res) vst[e] = false;
    return res;
}

void dfs(ll cur) {
    vst[cur] = true;
    sz++;
    for (auto &e : adj[cur]) {
        if (vst[e]) continue;
        dfs(e);
    }
}
 
vector<int> longest_trip(int n, int d) {
    mt = mt19937(time(0));
    adj = vector<vector<ll>>(n);
    vst = vector<bool>(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);
            }
        }
    }

    sz = 0;
    vst = vector<bool>(n);
    dfs(0);
    bool comp0 = sz > n/2;

    ll start = 0;
    for (int i = 0; i < n; i++) {
        if (comp0 != vst[i]) continue;
        start = i;
        break;
    }
    for (int i = 0; i < n; i++) {
        if (comp0 != vst[i]) continue;
        if (adj[i].size() == 1) start = i;
    }
    
    vst = vector<bool>(n);
    vector<int> res;
    for (int i = 0; i < 1; i++) {
        vector<int> nw = mxRand(start);
        if (nw.size() > res.size()) res = nw;
    }
    return res;
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> mxRand(ll)':
longesttrip.cpp:13:8: warning: unused variable 'n' [-Wunused-variable]
   13 |     ll n = adj.size();
      |        ^

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