Submission #948102

#	Time	Username	Problem	Language	Result	Execution time	Memory
948102		Nhoksocqt1	Thousands Islands (IOI22_islands)	C++17	10 / 100	108 ms	19876 KiB

islands

#ifndef Nhoksocqt1
    #include "islands.h"
#endif // Nhoksocqt1
#include<bits/stdc++.h>
using namespace std;

#define inf 0x3f3f3f3f
#define sz(x) int((x).size())
#define fi first
#define se second
typedef long long ll;
typedef pair<int, int> ii;

template<class X, class Y>
	inline bool maximize(X &x, const Y &y) {return (x < y ? x = y, 1 : 0);}
template<class X, class Y>
	inline bool minimize(X &x, const Y &y) {return (x > y ? x = y, 1 : 0);}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int Random(int l, int r) {
    return uniform_int_distribution<int>(l, r)(rng);
}

const int MAXN = 100005;

vector<ii> adj[MAXN];
map<ii, int> cntEdge;
ii edge[2 * MAXN];
int numNode, numEdge;

int getCntEdge(ii p) {
    return (cntEdge.find(p) != cntEdge.end()) ? cntEdge[p] : 0;
}

#ifdef Nhoksocqt1
    vector<int>
#else
    variant<bool, vector<int>>
#endif // Nhoksocqt1
    find_journey(int _N, int _M, vector<int> _U, vector<int> _V) {
    numNode = _N, numEdge = _M;
    for (int i = 0; i < numEdge; ++i) {
        int u(_U[i]), v(_V[i]);
        edge[i] = {u, v};
        adj[u].push_back(ii(v, i));
        adj[v].push_back(ii(u, i));
        ++cntEdge[ii(u, v)];
    }

    int x(-1), y(-1);
    for (int i = 1; i < numNode; ++i) {
        if(getCntEdge(ii(0, i)) > 1 && getCntEdge(ii(i, 0)) > 0) {
            x = i;
            break;
        }
    }

    if(x != -1) {
        int cnt0(0), cnt1(0);
        for (int i = 0; i < numEdge; ++i) {
            cnt0 += (edge[i].fi == 0);
            cnt1 += (edge[i].fi == x);
        }

        int id0_1(-1), id0_2(-1), idx(-1);
        for (int i = 0; i < numEdge; ++i) {
            if(edge[i].fi == 0) {
                if(id0_1 < 0) {
                    id0_1 = i;
                } else {
                    id0_2 = i;
                }
            } else {
                idx = i;
            }
        }

        vector<int> ans({id0_1, idx, id0_2, id0_1, idx, id0_2});
        return ans;
    }

    for (int i = 1; i < numNode; ++i) {
        if(getCntEdge(ii(0, i)) > 0 && getCntEdge(ii(i, 0)) > 0) {
            if(x < 0) {
                x = i;
            } else {
                y = i;
            }
        }
    }

    if(y >= 0) {
        int id0_x(-1), idx_0(-1), id0_y(-1), idy_0(-1);
        for (int i = 0; i < numEdge; ++i) {
            int u(edge[i].fi), v(edge[i].se);
            if(u == 0 && v == x)
                id0_x = i;

            if(u == x && v == 0)
                idx_0 = i;

            if(u == 0 && v == y)
                id0_y = i;

            if(u == y && v == 0)
                idy_0 = i;
        }

        vector<int> ans({id0_x, idx_0, id0_y, idy_0, idx_0, id0_x, idy_0, id0_y});
        return ans;
    }

    x = y = -1;

    #ifdef Nhoksocqt1
        return {-1};
    #else
        return false;
    #endif // Nhoksocqt1
}

#ifdef Nhoksocqt1

int main(void) {
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    #define TASK "islands"
    if(fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }

    vector<int> _U, _V;
    int _N, _M;
    cin >> _N >> _M;

    _U.resize(_M), _V.resize(_M);
    for (int i = 0; i < _M; ++i)
        cin >> _U[i] >> _V[i];

    vector<int> p = find_journey(_N, _M, _U, _V);
    cout << "ANSWER: ";
    if(sz(p) == 1 && p[0] == -1) {
        cout << "NO\n";
    } else {
        for (int it = 0; it < sz(p); ++it)
            cout << p[it] << ' ';

        cout << '\n';
    }

    return 0;
}

#endif // Nhoksocqt1

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