Submission #1059667

#	Time	Username	Problem	Language	Result	Execution time	Memory
1059667		shiomusubi496	Thousands Islands (IOI22_islands)	C++17	19.25 / 100	32 ms	10452 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), RG(N);
    rep (i, M) {
        G[U[i]].push_back({V[i], i});
        RG[V[i]].push_back({U[i], i});
    }
    vector<int> memo;
    int cur = 0;
    {
        vector<bool> seen(N, false);
        while (1) {
            seen[cur] = true;
            vector<edge> nxts;
            for (auto e : G[cur]) {
                if (!seen[e.to]) nxts.push_back(e);
            }
            if (nxts.size() == 0) return false;
            if (nxts.size() >= 2) break;
            memo.push_back(nxts[0].idx);
            cur = nxts[0].to;
        }
    }
    vector<int> deg(N);
    rep (i, M) ++deg[U[i]];
    queue<int> que;
    rep (i, N) {
        if (deg[i] == 0) que.push(i);
    }
    while (!que.empty()) {
        int v = que.front(); que.pop();
        for (auto e : RG[v]) {
            --deg[e.to];
            if (deg[e.to] == 0) que.push(e.to);
        }
    }
    if (deg[cur] == 0) return false;
    return true;
}

• Subtask 1: 1.75 / 5
• Subtask 2: 1.75 / 5
• Subtask 3: 7.35 / 21
• Subtask 4: 8.399999999999999 / 24
• Subtask 5: 0 / 45