Submission #1010820

#	Time	Username	Problem	Language	Result	Execution time	Memory
1010820		GrindMachine	수천개의 섬 (IOI22_islands)	C++17	8.40 / 100	70 ms	15308 KiB

islands

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

#include "islands.h"

vector<pii> adj[N];
vector<bool> vis(N), recstack(N);
vector<pii> par(N,{-1,-1});
bool cyc = false;
vector<int> cyc_edges;
vector<int> ans;

void dfs1(int u){
    vis[u] = 1;
    recstack[u] = 1;

    for(auto [v,id] : adj[u]){
        if(vis[v]){
            if(recstack[v]){
                if(!cyc){
                    cyc = true;
                    int curr = u;
                    while(curr != v){
                        cyc_edges.pb(par[curr].ss);
                        curr = par[curr].ff;
                    }
                    reverse(all(cyc_edges));
                    cyc_edges.pb(id);

                    vector<int> par_edges;
                    curr = v;
                    while(curr){
                        par_edges.pb(par[curr].ss);
                        curr = par[curr].ff;
                    }

                    ans = par_edges;
                    reverse(all(ans));

                    int siz = sz(cyc_edges);
                    cyc_edges.pb(cyc_edges[0]^1);

                    rep(iter,siz){
                        trav(x,cyc_edges){
                            ans.pb(x);
                        }
                    }

                    trav(x,par_edges) ans.pb(x);
                }
            }
        }
        else{
            par[v] = {u,id};
            dfs1(v);
        }
    }

    recstack[u] = 0;
}

bool line = true;
vector<bool> good(N);

void dfs2(int u, int p){
    vis[u] = 1;
    int d = sz(adj[u])-(p != -1);
    if(d >= 2){
        good[u] = 1;
        line = false;
    }

    for(auto [v,id] : adj[u]){
        if(v == p or vis[v]) conts;
        par[v] = {u,id};
        dfs2(v,u);
    }
}

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 += 2){
        int u = U[i], v = V[i];
        adj[u].pb({v,i});
    }

    dfs1(0);
    if(!cyc) return false;

    assert(sz(ans) <= 2e6);
    rep(i,sz(ans)-1) assert(ans[i] != ans[i+1]);
    return ans;    
}

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