Submission #824269

#	Time	Username	Problem	Language	Result	Execution time	Memory
824269		Liudas	Thousands Islands (IOI22_islands)	C++17	10 / 100	245 ms	5232 KiB

islands

#include "islands.h"
#include <cassert>
#include <cstdio>
#include <variant>
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
    if (N == 2){
        if(count(U.begin(), U.end(), 0) >= 2 && count(U.begin(), U.end(), 1) >= 1){
            vector<pair<int, int>> ans(M);
            for(int i = 0; i < M; i ++){
                ans[i] = {U[i], i};
            }
            sort(ans.begin(), ans.end());
            vector<int> ret = {ans[0].second, ans.back().second, ans[1].second, ans[0].second, ans.back().second, ans[1].second};
            return ret;
        }
        return false;
    }
    bool N2 = true;
    for(int i = 0; i < N; i ++){
        N2 &= ((count(U.begin(), U.end(), i) + count(V.begin(), V.end(), i)) == 2 * N - 2);
    }
    if(N2){
        vector<vector<pair<int, int>>> tree(N);
        for(int i = 0; i < M; i ++){
            tree[U[i]].push_back({V[i], i});
        }
        for(int i = 0; i < N; i ++){
            sort(tree[i].begin(), tree[i].end());
        }
        vector<int> ret = {tree[0][0].second, tree[1][0].second, tree[0][1].second, tree[2][0].second, tree[1][0].second, tree[0][0].second, tree[2][0].second, tree[0][1].second};
        return ret;
    }
    vector<vector<pair<int,int>>> tree(N);
    for(int i = 0; i < M; i ++){
        tree[U[i]].push_back({V[i], i});
    }
    int id = 0, par = -1;
    bool back = false;
    while(tree[id].size() < 2 && !back){
        if(tree[id].size() == 1){
            id = tree[id][0].first;
        }
        else{
            if(tree[id][0].first == par)
                id = tree[id][1].first;
            else
                id = tree[id][0].first;
        }
        par = id;
        if(id == 0){
            back = true;
        }
    }
    //back |= tree[0].size() > 1;
    //cout << back << endl;
    if(back){
        return false;
    }
    else{
        vector<int> ans = {0, 0, 0};
        return ans;
    }
}

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