Submission #632012

#	Time	Username	Problem	Language	Result	Execution time	Memory
632012		typ_ik	Thousands Islands (IOI22_islands)	C++17	5 / 100	34 ms	4424 KiB

islands

#include "islands.h"

#include <bits/stdc++.h>
#include <variant>

#define ll long long
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define watch(x) cout << (#x) << " = " << x << '\n'
#define boost ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)

using namespace std;

map < pair<int,int>,vector<int> > cnt;
vector < int > ans;
bool ok = true;

void dfs(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]);
}

void go(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]);
}

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++){
        dfs(i,i+1);
    }
    for(int i = N-2; i >= 0; i--){
        go(i,i+1);
        if(!ok)  return false;
    }
    return ans;
}

Compilation message (stderr)

islands.cpp: In function 'void dfs(int, int)':
islands.cpp:20:19: warning: variable 'B' set but not used [-Wunused-but-set-variable]
   20 |     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