Submission #628874

#	Time	Username	Problem	Language	Result	Execution time	Memory
628874		welleyth	Thousands Islands (IOI22_islands)	C++17	5 / 100	41 ms	4428 KiB

islands

#include "islands.h"

#include <variant>
#include <vector>
#include <bits/stdc++.h>
using namespace std;
map<pair<int,int>,vector<int>> cnt;
vector<int> ans;
bool ok = true;

void go1(int a,int b){
    pair<int,int> A = {a,b};
    pair<int,int> B = {b,a};
    if(cnt[A].size() == 0){
        ok = false;
        return;
    }
    ans.push_back(cnt[A][0]);
    return;
}
void go2(int a,int b){
    pair<int,int> A = {a,b};
    pair<int,int> B = {b,a};
    if(cnt[B].size() == 0){
        ok = false;
        return;
    }
    ans.push_back(cnt[B][0]);
    if(cnt[A].size() < 2){
        ok = false;
        return;
    }
    ans.push_back(cnt[A][1]);
    ans.push_back(cnt[A][0]);
    ans.push_back(cnt[B][0]);
    ans.push_back(cnt[A][1]);
    return;
}

std::variant<bool, std::vector<int>> find_journey(
    int N, int M, std::vector<int> U, std::vector<int> V) {
    for(int i = 0; i < M; i++){
        cnt[{U[i],V[i]}].push_back(i);
    }
    for(int i = 0; i + 1 < N; i++){
        go1(i,i+1);
    }
    for(int i = N-2; i >= 0; i--){
        go2(i,i+1);
        if(!ok)
            return false;
    }
    return ans;
}

Compilation message (stderr)

islands.cpp: In function 'void go1(int, int)':
islands.cpp:13:19: warning: variable 'B' set but not used [-Wunused-but-set-variable]
   13 |     pair<int,int> B = {b,a};
      |                   ^

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