Submission #826397

#	Time	Username	Problem	Language	Result	Execution time	Memory
826397		alvingogo	Thousands Islands (IOI22_islands)	C++17	10.15 / 100	34 ms	6968 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
#include <variant>
#define fs first
#define sc second
using namespace std;

vector<vector<pair<int,int> > > e;
vector<int> dep,fa;
vector<int> ss;
vector<int> ans;
int dfs(int r,int f){
    dep[r]=dep[f]+1;
    fa[r]=f;
    for(auto h:e[r]){
        if(ss[h.sc/2]){
            continue;
        }
        ss[h.sc/2]=1;
        if(dep[h.fs]==-1){
            if(dfs(h.fs,r)){
                return 1;
            }
        }
        else if(dep[h.fs]>=0){
            vector<int> bz;
            for(int i=0;i!=h.fs;){
                for(auto w:e[i]){
                    if(dep[w.fs]==dep[i]+1){
                        bz.push_back(w.sc);
                        i=w.fs;
                        break;
                    }
                }
            }
            vector<int> cz,dz;
            for(int i=h.fs;i!=r;){
                for(auto w:e[i]){
                    if(dep[w.fs]==dep[i]+1 && ss[w.sc/2]){
                        cz.push_back(w.sc);
                        dz.push_back(w.sc^1);
                        i=w.fs;
                        break;
                    }
                }
            }
            cz.push_back(h.sc);
            dz.push_back(h.sc^1);
            reverse(dz.begin(),dz.end());
            ans.insert(ans.end(),bz.begin(),bz.end());
            ans.insert(ans.end(),cz.begin(),cz.end());
            ans.insert(ans.end(),dz.begin(),dz.end());
            reverse(bz.begin(),bz.end());
            reverse(cz.begin(),cz.end());
            reverse(dz.begin(),dz.end());
            ans.insert(ans.end(),cz.begin(),cz.end());
            ans.insert(ans.end(),dz.begin(),dz.end());
            ans.insert(ans.end(),bz.begin(),bz.end());
            return 1;
        }
    }
    dep[r]=-2;
    return 0;
}
variant<bool, vector<int>> find_journey(
    int n, int m, vector<int> u, vector<int> v) {
    e.resize(n);
    fa.resize(n);
    ss.resize(m);
    dep.resize(n,-1);
    for(int i=0;i<m;i++){
        e[u[i]].push_back({v[i],i});
    }
    if(!dfs(0,0)){
        return false;
    }
    return ans;
}

• Subtask 1: 0 / 5
• Subtask 2: 1.75 / 5
• Subtask 3: 0 / 21
• Subtask 4: 8.399999999999999 / 24
• Subtask 5: 0 / 45