Submission #1183764

#	Time	Username	Problem	Language	Result	Execution time	Memory
1183764		gyg	Thousands Islands (IOI22_islands)	C++20	22.75 / 100	21 ms	7496 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
using namespace std;
#define arr array
#define vec vector 
#define var variant
#define pii pair<int, int>
#define fir first 
#define sec second
const int N = 1e5 + 5;

int n, m;
arr<vec<pii>, N> adj;

vec<int> ans;
arr<bool, N> vs;
bool dfs(int u = 1) {
    vs[u] = true;

    vec<pii> ngh;
    for (auto [v, i] : adj[u])
        if (!vs[v]) ngh.push_back({v, i});

    if (ngh.size() <= 1) {
        for (auto [v, i] : ngh) {
            ans.push_back(i);
            if (dfs(v)) return true;
        }
        return false;
    }    

    int a = ngh[0].sec, b = (a % 2 == 0) ? a + 1 : a - 1;
    int c = ngh[1].sec, d = (c % 2 == 0) ? c + 1 : c - 1;
    
    vec<int> x = ans;     
    vec<int> y = {a, b, c, d, b, a, d, c};
    vec<int> z = ans;
    reverse(z.begin(), z.end());

    ans.clear();
    for (vec<int> w : {x, y, z})
        ans.insert(ans.end(), w.begin(), w.end());
    return true;
}

var<bool, vec<int>> find_journey(int _n, int _m, vec<int> _u, vec<int> _v) {
    n = _n, m = _m;
    for (int i = 0; i < m; i++) {
        int u = _u[i] + 1, v = _v[i] + 1;
        adj[u].push_back({v, i});
    }

    if (!dfs()) return false;
    return ans;
}

• Subtask 1: 0 / 5
• Subtask 2: 1.75 / 5
• Subtask 3: 21 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45