Submission #835596

#	Time	Username	Problem	Language	Result	Execution time	Memory
835596		gagik_2007	Thousands Islands (IOI22_islands)	C++17	22.75 / 100	28 ms	7524 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define ff first
#define ss second

ll ttt;
const ll INF=1e18;
const ll MOD=1e9+7;
const ll N=100007;
ll n,m,k;
vector<pair<int,int>>g[N];
bool used[N];
deque<int>path;

int inv(int x){
    if(x%2==0){
        return x+1;
    }
    return x-1;
}

bool dfs(int v){
    if(used[v])return false;
    used[v]=true;
    if(g[v].size()>=3){
        if(used[g[v][0].ff])swap(g[v][0],g[v][1]);
        if(used[g[v][1].ff])swap(g[v][1],g[v][2]);
        path.push_back(g[v][0].ss);
        path.push_back(inv(g[v][0].ss));
        path.push_back(g[v][1].ss);
        path.push_back(inv(g[v][1].ss));
        path.push_back(inv(g[v][0].ss));
        path.push_back(g[v][0].ss);
        path.push_back(inv(g[v][1].ss));
        path.push_back(g[v][1].ss);
        return true;
    }
    for(pair<int,int> to:g[v]){
        if(dfs(to.ff)){
            path.push_front(to.ss);
            path.push_back(to.ss);
            return true;
        }
    }
    return false;
}

variant<bool, vector<int>> find_journey(int NN, int MM, vector<int> U, vector<int> V) {
    n=NN;
    m=MM;
    for(int i=0;i<m;i++){
        g[U[i]].push_back({V[i],i});
    }
    if(g[0].size()>=2){
        vector<int>ans = {g[0][0].ss,inv(g[0][0].ss),
                          g[0][1].ss,inv(g[0][1].ss),
                          inv(g[0][0].ss),g[0][0].ss,
                          inv(g[0][1].ss),g[0][1].ss};
        return ans;
    }
    if(dfs(0)){
        vector<int>ans;
        for(int x:path)ans.push_back(x);
        return ans;
    }
    return false;
}

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