Submission #1028924

#	Time	Username	Problem	Language	Result	Execution time	Memory
1028924		Mardonbekhazratov	Thousands Islands (IOI22_islands)	C++17	10 / 100	87 ms	23524 KiB

islands

#include "islands.h"

#include <variant>
#include <iostream>
#include <vector>
#include <algorithm>
#include <tuple>
#include <map>

using namespace std;

int n,m;
vector<int>u,v;

variant<bool,vector<int>>sub1(){
    vector<int>c1,c2;
    for(int i=0;i<m;i++){
        if(u[i]==0) c1.push_back(i);
        else c2.push_back(i);
    }
    if(c1.size()<2 || c2.size()<1) return false;
    return vector<int>({c1[0],c2[0],c1[1],c1[0],c2[0],c1[1]});
}

vector<int>sub2(){
    vector<vector<int>>a(3,vector<int>(3));
    for(int i=0;i<m;i++){
        if(u[i]<3 && v[i]<3) a[u[i]][v[i]]=i;
    }
    return vector<int>({a[0][1],a[1][0],a[0][2],a[2][1],a[0][1],a[1][0],a[2][1],a[0][2]});
}

vector<vector<int>>adj;
vector<int>vis,cf,cycle;
bool found;
vector<map<int,vector<int>>>b;

variant<bool,vector<int>>dfs(int x){
    vis[x]=true;
    if(adj[x].size()>1){
        int y=adj[x][0],z=adj[x][1];
        int j=y==z;
        vector<int>asn={b[x][y][0],b[y][x][0],b[x][z][j],b[z][x][j],b[y][x][0],b[x][y][0],b[z][x][j],b[x][z][j]};
        return asn;
    }
    for(int z:adj[x]){
        if(vis[z]) continue;
        variant<bool,vector<int>>res=dfs(z);
        if(res.index()==0) return false;
        vector<int>sm=get<vector<int>>(res);
        vector<int>asn={b[x][z][0]};
        for(int h:sm) asn.push_back(h);
        asn.push_back(b[x][z][0]);
        return asn;
    }
    return false;
}

variant<bool,vector<int>>sub3(){
    adj.resize(n);
    b.resize(n);
    for(int i=0;i<m;i++){
        adj[u[i]].push_back(v[i]);
        b[u[i]][v[i]].push_back(i);
    } 
    vis.assign(n,0);
    found=false;
    cf.resize(n);
    return dfs(0);
}

std::variant<bool, std::vector<int>> find_journey(int N, int M, std::vector<int> U, std::vector<int> V) {
    tie(n,m,u,v)=tie(N,M,U,V);
    if(n==2) return sub1();
    return sub3();
}


/*
4 8
0 1
1 0
1 2
2 1
2 3
3 2
0 3
3 0
*/

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