Submission #652861

#	Time	Username	Problem	Language	Result	Execution time	Memory
652861		Lobo	Thousands Islands (IOI22_islands)	C++17	9.10 / 100	1139 ms	1507988 KiB

islands

#include "islands.h"
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fr first
#define sc second
#define mp make_pair

const int maxn = 2e5+10;
int n, m, tin[maxn], low[maxn], mark[maxn], iscyc[maxn], can0[maxn], timer;
vector<int> g[maxn], gt[maxn];
vector<pair<int,int>> gid[maxn];
map<int,vector<int>> boats[maxn];
vector<int> cur, final;
int cycbeg = -1;
void dfs(int u, int ant) {
    if(g[u].size() >= 3 || (g[u].size() == 2 && u == 0)) {
        final = cur;
        vector<int> i1s;
        for(auto x : gid[u]) {
            if(i1s.size() != 2 && x.sc/2 != ant/2) i1s.pb(x.sc);
        }
        final.pb(i1s[0]);
        final.pb(i1s[1]);
    }

    if(final.size()) return;
    for(auto V : gid[u]) if(V.sc/2 != ant/2) {
        if(final.size()) return;
        cur.pb(V.sc);
        dfs(V.fr,V.sc);
        cur.pop_back();
    }
}

void dfs0(int u) {
    can0[u] = 1;
    for(auto v : g[u]) {
        if(can0[v] == 0) dfs0(v);
    }
}

variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
    n = N;
    m = M;
    for(int i = 0; i < m; i++) {
        g[U[i]].pb(V[i]);
        gid[U[i]].pb(mp(V[i],i));
        gt[V[i]].pb(U[i]);
        boats[U[i]][V[i]].pb(i);
    }

    dfs(0,-10);
    dfs0(0);

    if(final.size()) {
        return true;
    }
    return false;

}

• Subtask 1: 0 / 5
• Subtask 2: 1.75 / 5
• Subtask 3: 7.35 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45