Submission #1059639

#	Time	Username	Problem	Language	Result	Execution time	Memory
1059639		shiomusubi496	Thousands Islands (IOI22_islands)	C++17	11.90 / 100	24 ms	7764 KiB

islands

#include "islands.h"

#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep2(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rrep(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define rrep2(i, a, b) for (int i = (int)(b) - 1; i >= (int)(a); --i)

#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)

using namespace std;

using ll = long long;

template<class T, class U> bool chmin(T& a, const U& b) { return a > b ? a = b, true : false; }
template<class T, class U> bool chmax(T& a, const U& b) { return a < b ? a = b, true : false; }

struct edge {
    int to, idx;
};

using Graph = vector<vector<edge>>;

std::variant<bool, std::vector<int>> find_journey(int N, int M, std::vector<int> U, std::vector<int> V) {
    Graph G(N);
    rep (i, M) G[U[i]].push_back({V[i], i});
    queue<int> que;
    vector<bool> seen(N, false), used(N, false);
    vector<bool> cycle1(N, false);
    que.push(0);
    while (!que.empty()) {
        int s = -1;
        bool flag = false;
        vector<int> cs;
        auto dfs = [&](auto&& self, int v) -> void {
            seen[v] = used[v] = true;
            for (auto e : G[v]) {
                if (used[e.to]) {
                    if (s == -1) {
                        s = e.to;
                        cycle1[v] = true;
                        cs.push_back(v);
                        break;
                    }
                    else {
                        flag = true;
                        break;
                    }
                }
                if (cycle1[e.to]) {
                    flag = true;
                    break;
                }
                if (seen[e.to]) continue;
                self(self, e.to);
                if (flag) break;
                if (s >= 0) {
                    cycle1[v] = true;
                    cs.push_back(v);
                    if (s != v) break;
                    s = -2;
                }
            }
            used[v] = false;
        };
        int v = que.front(); que.pop();
        dfs(dfs, v);
        if (flag) return true;
        for (int i : cs) cycle1[i] = false;
        for (int i : cs) if (i != cs.back()) que.push(i);
    }
    return false;
}

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