oj.uz

Submission #948157

# Submission time Handle Problem Language Result Execution time Memory
948157 2024-03-17T17:02:52 Z Nhoksocqt1 Thousands Islands (IOI22_islands) C++17
13.4 / 100
 189 ms 17492 KB 
#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 low[MAXN], num[MAXN], tr[MAXN], numNode, numEdge;
bool dx[MAXN], dxt[2 * MAXN];

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

void dfs(int u, int lastID = -1) {
    dx[u] = 1;
    tr[u] = lastID;
    for (int it = 0; it < sz(adj[u]); ++it) {
        int v(adj[u][it].fi), id(adj[u][it].se);
        if(!dx[v])
            dfs(v, id);
    }
}

stack<int> st;
bool tarjan(int u) {
    st.push(u);
    low[u] = num[u] = ++num[numNode];

    for (int it = 0; it < sz(adj[u]); ++it) {
        int v(adj[u][it].fi), id(adj[u][it].se);
        if(!dxt[id]) {
            dxt[id] = 1;
            if(!num[v]) {
                if(tarjan(v))
                    return true;

                low[u] = min(low[u], low[v]);
            } else {
                low[u] = min(low[u], num[v]);
            }
        }
    }

    if(low[u] == num[u]) {
        int v, cnt(0);
        do {
            v = st.top(); st.pop();
            low[v] = num[v] = 1e9+7;
            ++cnt;
        } while(v != u);
        return (cnt > 2);
    }

    return false;
}

#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};
        ++cntEdge[ii(u, v)];
    }

    for (int i = 0; i < numEdge; ++i) {
        int u(edge[i].fi), v(edge[i].se);
        if(getCntEdge(ii(u, v)) > 1)
            adj[u].push_back(ii(v, i));
    }

    dfs(0);
    int x(-1), y(-1), z(-1);
    for (int i = 0; i < numNode; ++i) {
        if(dx[i]) {
            int t1(-1);
            for (int it = 0; it < sz(adj[i]); ++it) {
                int j(adj[i][it].fi);

                if(edge[tr[i]].fi != j && getCntEdge(ii(j, i)) > 0) {
                    if(t1 < 0) {
                        t1 = j;
                    } else
                        if(t1 != j) {
                            x = i, y = t1, z = j;
                            break;
                        }
                }
            }

            if(y >= 0)
                break;
        }
    }

    if(z >= 0) {
        int idx_y(-1), idy_x(-1), idx_z(-1), idz_x(-1);
        for (int i = 0; i < numEdge; ++i) {
            int u(edge[i].fi), v(edge[i].se);
            if(u == x && v == y)
                idx_y = i;

            if(u == y && v == x)
                idy_x = i;

            if(u == x && v == z)
                idx_z = i;

            if(u == z && v == x)
                idz_x = i;
        }

        vector<int> ans, pf;
        int u(x);
        while(u != 0) {
            ans.push_back(tr[u]);
            u = edge[tr[u]].fi;
        }

        pf = ans;
        reverse(ans.begin(), ans.end());

        vector<int> p({idx_y, idy_x, idx_z, idz_x, idy_x, idx_y, idz_x, idx_z});
        for (int it = 0; it < sz(p); ++it)
            ans.push_back(p[it]);

        for (int it = 0; it < sz(pf); ++it)
            ans.push_back(pf[it]);

        return ans;
    }

    for (int i = 0; i < numNode; ++i) {
        if(!dx[i])
            continue;

        for (int it = 0; it < sz(adj[i]); ++it) {
            int j(adj[i][it].fi);
            if(edge[tr[i]].fi != j && getCntEdge(ii(i, j)) > 1 && getCntEdge(ii(j, i)) > 0) {
                x = i, y = j;
                break;
            }
        }

        if(y >= 0)
            break;
    }

    if(y >= 0) {
        int idx_y_1(-1), idy_x(-1), idx_y_2(-1);
        for (int i = 0; i < numEdge; ++i) {
            int u(edge[i].fi), v(edge[i].se);
            if(u == x && v == y) {
                if(idx_y_1 < 0) {
                    idx_y_1 = i;
                } else {
                    idx_y_2 = i;
                }
            }

            if(u == y && v == x)
                idy_x = i;
        }

        vector<int> ans, pf;
        int u(x);
        while(u != 0) {
            ans.push_back(tr[u]);
            u = edge[tr[u]].fi;
        }

        pf = ans;
        reverse(ans.begin(), ans.end());

        vector<int> p({idx_y_1, idy_x, idx_y_2, idx_y_1, idy_x, idx_y_2});
        for (int it = 0; it < sz(p); ++it)
            ans.push_back(p[it]);

        for (int it = 0; it < sz(pf); ++it)
            ans.push_back(pf[it]);

        return ans;
    }

    for (int i = 0; i <= numNode; ++i)
        low[i] = num[i] = 0;

    if(tarjan(0))
        return true;

    #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
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 5468 KB Output is correct
2 Correct 1 ms 5468 KB Output is correct
3 Correct 1 ms 5464 KB Output is correct
4 Correct 1 ms 5468 KB Output is correct
5 Correct 2 ms 5468 KB Output is correct
6 Correct 1 ms 5468 KB Output is correct
7 Correct 31 ms 10420 KB Output is correct

Subtask #2
0.0 / 5.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 5468 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #3
0.0 / 21.0

# Verdict Execution time Memory Grader output
1 Incorrect 3 ms 5724 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
8.4 / 24.0

# Verdict Execution time Memory Grader output
1 Partially correct 2 ms 5468 KB Output is partially correct
2 Partially correct 3 ms 5724 KB Output is partially correct
3 Correct 70 ms 10524 KB Output is correct
4 Correct 111 ms 14752 KB Output is correct
5 Partially correct 4 ms 5724 KB Output is partially correct
6 Correct 3 ms 5876 KB Output is correct
7 Correct 1 ms 5468 KB Output is correct
8 Correct 1 ms 5464 KB Output is correct
9 Correct 1 ms 5468 KB Output is correct
10 Correct 3 ms 5724 KB Output is correct
11 Correct 4 ms 5720 KB Output is correct
12 Partially correct 4 ms 5724 KB Output is partially correct
13 Partially correct 4 ms 5720 KB Output is partially correct
14 Correct 3 ms 5724 KB Output is correct
15 Correct 5 ms 5980 KB Output is correct
16 Partially correct 2 ms 5724 KB Output is partially correct
17 Correct 1 ms 5468 KB Output is correct
18 Correct 3 ms 5724 KB Output is correct
19 Correct 2 ms 5724 KB Output is correct
20 Correct 96 ms 11352 KB Output is correct
21 Partially correct 133 ms 15696 KB Output is partially correct
22 Correct 3 ms 5720 KB Output is correct
23 Correct 2 ms 5468 KB Output is correct
24 Correct 1 ms 5676 KB Output is correct
25 Partially correct 2 ms 5724 KB Output is partially correct
26 Partially correct 2 ms 5724 KB Output is partially correct
27 Correct 109 ms 14364 KB Output is correct
28 Correct 121 ms 14928 KB Output is correct
29 Correct 1 ms 5468 KB Output is correct
30 Correct 189 ms 17492 KB Output is correct
31 Partially correct 1 ms 5464 KB Output is partially correct
32 Correct 131 ms 15264 KB Output is correct
33 Correct 88 ms 11004 KB Output is correct
34 Correct 54 ms 11344 KB Output is correct
35 Partially correct 2 ms 5724 KB Output is partially correct
36 Correct 114 ms 14052 KB Output is correct
37 Partially correct 177 ms 16612 KB Output is partially correct
38 Correct 2 ms 5724 KB Output is correct
39 Correct 141 ms 13884 KB Output is correct
40 Partially correct 3 ms 5720 KB Output is partially correct
41 Correct 185 ms 17128 KB Output is correct
42 Correct 132 ms 15188 KB Output is correct
43 Correct 2 ms 5664 KB Output is correct
44 Correct 4 ms 5724 KB Output is correct
45 Partially correct 3 ms 5724 KB Output is partially correct
46 Correct 43 ms 10332 KB Output is correct

Subtask #5
0.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 5468 KB Output is correct
2 Correct 1 ms 5468 KB Output is correct
3 Correct 1 ms 5464 KB Output is correct
4 Correct 1 ms 5468 KB Output is correct
5 Correct 2 ms 5468 KB Output is correct
6 Correct 1 ms 5468 KB Output is correct
7 Correct 31 ms 10420 KB Output is correct
8 Incorrect 2 ms 5468 KB Output isn't correct
9 Halted 0 ms 0 KB -