Submission #628526

#	Time	Username	Problem	Language	Result	Execution time	Memory
628526		Sorting	Thousands Islands (IOI22_islands)	C++17	6.75 / 100	37 ms	5284 KiB

islands

#include "islands.h"

#include <variant>
#include <vector>
#include <algorithm>
#include <cmath>

using namespace std;

std::variant<bool, std::vector<int>> find_journey(
    int n, int m, std::vector<int> u, std::vector<int> v) {
    if(n == 2){
        vector<int> cnt[2]{};
        for(int i = 0; i < u.size();++i){
            cnt[u[i]].push_back(i);
        }
        
        if(cnt[0].size() >= 2 && cnt[1].size() >= 1){
            return vector<int>{cnt[0][0], cnt[1][0], cnt[0][1], cnt[0][0], cnt[1][0], cnt[0][1]};
        }
        return false;
    }
    vector<vector<pair<int, int>>> adj(n);
    for(int i = 0; i < m; ++i)
        adj[u[i]].push_back({v[i], i});
    
    int x = 1, par = -1;
    vector<bool> vis(n);
    while(true){
        vis[x] = true;
        if(adj[x].size() != 1 + (x != 1)){
            if(adj[x].size() < 1 + (x != 1)){
                return false;
            }
            return true;
        }
        for(auto p: adj[x]){
            int to = p.first;
            int idx = p.second;
            if(to == par){
                par = -1;
                continue;
            }
            par = x;
            x = to;
            if(vis[x])
                return true;
        }
    }
}

Compilation message (stderr)

islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:14:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |         for(int i = 0; i < u.size();++i){
      |                        ~~^~~~~~~~~~
islands.cpp:39:17: warning: unused variable 'idx' [-Wunused-variable]
   39 |             int idx = p.second;
      |                 ^~~

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