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Submission #824028

# Submission time Handle Problem Language Result Execution time Memory
824028 2023-08-13T11:37:25 Z finn__ Thousands Islands (IOI22_islands) C++17
100 / 100
 284 ms 48784 KB 
#include <bits/stdc++.h>
using namespace std;

constexpr int N_MAX = 100000;

set<pair<int, int>> g[N_MAX], rg[N_MAX];
bitset<N_MAX> visited, in_dfs;

void delete_node(int u)
{
    vector<int> to_delete;
    for (auto const &[v, i] : g[u])
        rg[v].erase(make_pair(u, i));
    for (auto const &[v, i] : rg[u])
    {
        g[v].erase(make_pair(u, i));
        if (g[v].empty())
            to_delete.push_back(v);
    }
    g[u].clear();
    rg[u].clear();

    for (auto const &v : to_delete)
        delete_node(v);
}

int find_cycle(int u, vector<int> &cycle, vector<int> &path_to_cycle)
{
    if (in_dfs[u])
        return u;
    if (visited[u])
        return -1;

    visited[u] = 1;
    in_dfs[u] = 1;

    for (auto const &[v, i] : g[u])
    {
        int x = find_cycle(v, cycle, path_to_cycle);
        if (x != -1)
        {
            cycle.push_back(i);
            in_dfs[u] = 0;
            return u == x ? -1 : x;
        }
        else if (!cycle.empty())
        {
            path_to_cycle.push_back(i);
            in_dfs[u] = 0;
            return -1;
        }
    }

    in_dfs[u] = 0;
    return -1;
}

variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V)
{
    for (int i = 0; i < M; ++i)
        g[U[i]].emplace(V[i], i), rg[V[i]].emplace(U[i], i);
    for (int i = 0; i < N; ++i)
        if (g[i].empty())
            delete_node(i);

    int x = 0;
    vector<int> line;
    while (g[x].size() == 1)
    {
        int y = g[x].begin()->first;
        line.push_back(g[x].begin()->second);
        delete_node(x);
        x = y;
    }

    if (g[x].empty())
        return false;

    vector<int> cycle_a, path_to_cycle_a, cycle_b, path_to_cycle_b;
    find_cycle(x, cycle_a, path_to_cycle_a);
    visited.reset();
    g[x].erase(g[x].begin());
    find_cycle(x, cycle_b, path_to_cycle_b);
    assert(!cycle_a.empty() && !cycle_b.empty());

    reverse(cycle_a.begin(), cycle_a.end());
    reverse(cycle_b.begin(), cycle_b.end());
    reverse(path_to_cycle_a.begin(), path_to_cycle_a.end());
    reverse(path_to_cycle_b.begin(), path_to_cycle_b.end());

    vector<int> cycle_a_ind(M, -1);
    for (int i = 0; i < cycle_a.size(); ++i)
        cycle_a_ind[cycle_a[i]] = i;

    int common_a = -1, common_b = -1;
    for (int i = 0; i < cycle_b.size(); ++i)
        if (cycle_a_ind[cycle_b[i]] != -1)
        {
            common_a = cycle_a_ind[cycle_b[i]];
            common_b = i;
            break;
        }

    vector<int> tour = line;
    if (common_a == -1)
    {
        tour.insert(tour.end(), path_to_cycle_a.begin(), path_to_cycle_a.end());
        tour.insert(tour.end(), cycle_a.begin(), cycle_a.end());
        tour.insert(tour.end(), path_to_cycle_a.begin(), path_to_cycle_a.end());
        reverse(tour.end() - path_to_cycle_a.size(), tour.end());

        tour.insert(tour.end(), path_to_cycle_b.begin(), path_to_cycle_b.end());
        tour.insert(tour.end(), cycle_b.begin(), cycle_b.end());
        tour.insert(tour.end(), path_to_cycle_b.begin(), path_to_cycle_b.end());
        reverse(tour.end() - path_to_cycle_b.size(), tour.end());

        tour.insert(tour.end(), path_to_cycle_a.begin(), path_to_cycle_a.end());
        tour.insert(tour.end(), cycle_a.begin(), cycle_a.end());
        reverse(tour.end() - cycle_a.size(), tour.end());
        tour.insert(tour.end(), path_to_cycle_a.begin(), path_to_cycle_a.end());
        reverse(tour.end() - path_to_cycle_a.size(), tour.end());

        tour.insert(tour.end(), path_to_cycle_b.begin(), path_to_cycle_b.end());
        tour.insert(tour.end(), cycle_b.begin(), cycle_b.end());
        reverse(tour.end() - cycle_b.size(), tour.end());
        tour.insert(tour.end(), path_to_cycle_b.begin(), path_to_cycle_b.end());
        reverse(tour.end() - path_to_cycle_b.size(), tour.end());
    }
    else
    {
        tour.insert(tour.end(), path_to_cycle_a.begin(), path_to_cycle_a.end());
        tour.insert(tour.end(), cycle_a.begin(), cycle_a.end());
        tour.insert(tour.end(), path_to_cycle_a.begin(), path_to_cycle_a.end());
        reverse(tour.end() - path_to_cycle_a.size(), tour.end());

        tour.insert(tour.end(), path_to_cycle_b.begin(), path_to_cycle_b.end());
        tour.insert(tour.end(), cycle_b.begin(), cycle_b.begin() + common_b);

        rotate(cycle_a.begin(), cycle_a.begin() + common_a, cycle_a.end());
        tour.insert(tour.end(), cycle_a.begin(), cycle_a.end());
        reverse(tour.end() - cycle_a.size(), tour.end());

        tour.insert(tour.end(), cycle_b.begin(), cycle_b.begin() + common_b);
        reverse(tour.end() - common_b, tour.end());
        tour.insert(tour.end(), path_to_cycle_b.begin(), path_to_cycle_b.end());
        reverse(tour.end() - path_to_cycle_b.size(), tour.end());
    }

    tour.insert(tour.end(), line.begin(), line.end());
    reverse(tour.end() - line.size(), tour.end());

    return tour;
}

Compilation message

islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:92:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   92 |     for (int i = 0; i < cycle_a.size(); ++i)
      |                     ~~^~~~~~~~~~~~~~~~
islands.cpp:96:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   96 |     for (int i = 0; i < cycle_b.size(); ++i)
      |                     ~~^~~~~~~~~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9684 KB Output is correct
2 Correct 4 ms 9684 KB Output is correct
3 Correct 4 ms 9696 KB Output is correct
4 Correct 4 ms 9684 KB Output is correct
5 Correct 4 ms 9684 KB Output is correct
6 Correct 4 ms 9684 KB Output is correct
7 Correct 87 ms 33080 KB Output is correct

Subtask #2
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 9684 KB Output is correct
2 Correct 5 ms 9700 KB Output is correct
3 Correct 4 ms 9680 KB Output is correct
4 Correct 4 ms 9684 KB Output is correct
5 Correct 4 ms 9684 KB Output is correct
6 Correct 124 ms 28536 KB Output is correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 10192 KB Output is correct
2 Correct 4 ms 9700 KB Output is correct
3 Correct 5 ms 9684 KB Output is correct
4 Correct 4 ms 9696 KB Output is correct
5 Correct 5 ms 9940 KB Output is correct
6 Correct 4 ms 9700 KB Output is correct
7 Correct 5 ms 9812 KB Output is correct
8 Correct 5 ms 9684 KB Output is correct
9 Correct 5 ms 9636 KB Output is correct
10 Correct 5 ms 9940 KB Output is correct
11 Correct 4 ms 9684 KB Output is correct
12 Correct 5 ms 9940 KB Output is correct
13 Correct 4 ms 9684 KB Output is correct
14 Correct 4 ms 9684 KB Output is correct
15 Correct 4 ms 9684 KB Output is correct
16 Correct 4 ms 9684 KB Output is correct
17 Correct 64 ms 21632 KB Output is correct
18 Correct 44 ms 19300 KB Output is correct
19 Correct 4 ms 9604 KB Output is correct
20 Correct 4 ms 9696 KB Output is correct
21 Correct 4 ms 9704 KB Output is correct
22 Correct 4 ms 9684 KB Output is correct
23 Correct 153 ms 28424 KB Output is correct

Subtask #4
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9700 KB Output is correct
2 Correct 6 ms 10068 KB Output is correct
3 Correct 130 ms 30844 KB Output is correct
4 Correct 142 ms 30880 KB Output is correct
5 Correct 5 ms 10068 KB Output is correct
6 Correct 6 ms 10228 KB Output is correct
7 Correct 6 ms 9684 KB Output is correct
8 Correct 4 ms 9696 KB Output is correct
9 Correct 5 ms 9700 KB Output is correct
10 Correct 5 ms 10068 KB Output is correct
11 Correct 6 ms 10220 KB Output is correct
12 Correct 6 ms 10224 KB Output is correct
13 Correct 6 ms 10228 KB Output is correct
14 Correct 6 ms 10092 KB Output is correct
15 Correct 6 ms 10348 KB Output is correct
16 Correct 5 ms 9940 KB Output is correct
17 Correct 4 ms 9696 KB Output is correct
18 Correct 6 ms 10068 KB Output is correct
19 Correct 5 ms 9940 KB Output is correct
20 Correct 156 ms 32236 KB Output is correct
21 Correct 145 ms 30844 KB Output is correct
22 Correct 5 ms 10092 KB Output is correct
23 Correct 6 ms 9812 KB Output is correct
24 Correct 4 ms 9700 KB Output is correct
25 Correct 5 ms 9940 KB Output is correct
26 Correct 5 ms 10068 KB Output is correct
27 Correct 138 ms 32024 KB Output is correct
28 Correct 135 ms 32008 KB Output is correct
29 Correct 4 ms 9684 KB Output is correct
30 Correct 155 ms 32344 KB Output is correct
31 Correct 4 ms 9656 KB Output is correct
32 Correct 155 ms 30800 KB Output is correct
33 Correct 142 ms 31992 KB Output is correct
34 Correct 54 ms 21712 KB Output is correct
35 Correct 5 ms 9812 KB Output is correct
36 Correct 121 ms 28512 KB Output is correct
37 Correct 154 ms 32032 KB Output is correct
38 Correct 5 ms 9812 KB Output is correct
39 Correct 112 ms 27308 KB Output is correct
40 Correct 5 ms 9940 KB Output is correct
41 Correct 152 ms 32384 KB Output is correct
42 Correct 150 ms 31988 KB Output is correct
43 Correct 5 ms 9684 KB Output is correct
44 Correct 6 ms 10068 KB Output is correct
45 Correct 5 ms 10068 KB Output is correct
46 Correct 38 ms 19392 KB Output is correct

Subtask #5
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9684 KB Output is correct
2 Correct 4 ms 9684 KB Output is correct
3 Correct 4 ms 9696 KB Output is correct
4 Correct 4 ms 9684 KB Output is correct
5 Correct 4 ms 9684 KB Output is correct
6 Correct 4 ms 9684 KB Output is correct
7 Correct 87 ms 33080 KB Output is correct
8 Correct 4 ms 9684 KB Output is correct
9 Correct 5 ms 9700 KB Output is correct
10 Correct 4 ms 9680 KB Output is correct
11 Correct 4 ms 9684 KB Output is correct
12 Correct 4 ms 9684 KB Output is correct
13 Correct 124 ms 28536 KB Output is correct
14 Correct 6 ms 10192 KB Output is correct
15 Correct 4 ms 9700 KB Output is correct
16 Correct 5 ms 9684 KB Output is correct
17 Correct 4 ms 9696 KB Output is correct
18 Correct 5 ms 9940 KB Output is correct
19 Correct 4 ms 9700 KB Output is correct
20 Correct 5 ms 9812 KB Output is correct
21 Correct 5 ms 9684 KB Output is correct
22 Correct 5 ms 9636 KB Output is correct
23 Correct 5 ms 9940 KB Output is correct
24 Correct 4 ms 9684 KB Output is correct
25 Correct 5 ms 9940 KB Output is correct
26 Correct 4 ms 9684 KB Output is correct
27 Correct 4 ms 9684 KB Output is correct
28 Correct 4 ms 9684 KB Output is correct
29 Correct 4 ms 9684 KB Output is correct
30 Correct 64 ms 21632 KB Output is correct
31 Correct 44 ms 19300 KB Output is correct
32 Correct 4 ms 9604 KB Output is correct
33 Correct 4 ms 9696 KB Output is correct
34 Correct 4 ms 9704 KB Output is correct
35 Correct 4 ms 9684 KB Output is correct
36 Correct 153 ms 28424 KB Output is correct
37 Correct 5 ms 9684 KB Output is correct
38 Correct 4 ms 9696 KB Output is correct
39 Correct 4 ms 9700 KB Output is correct
40 Correct 5 ms 9812 KB Output is correct
41 Correct 67 ms 19988 KB Output is correct
42 Correct 7 ms 10196 KB Output is correct
43 Correct 108 ms 29132 KB Output is correct
44 Correct 87 ms 29196 KB Output is correct
45 Correct 104 ms 29148 KB Output is correct
46 Correct 4 ms 9684 KB Output is correct
47 Correct 4 ms 9696 KB Output is correct
48 Correct 4 ms 9684 KB Output is correct
49 Correct 5 ms 9828 KB Output is correct
50 Correct 113 ms 28064 KB Output is correct
51 Correct 234 ms 48024 KB Output is correct
52 Correct 273 ms 47972 KB Output is correct
53 Correct 236 ms 48784 KB Output is correct
54 Correct 241 ms 48072 KB Output is correct
55 Correct 284 ms 48060 KB Output is correct
56 Correct 249 ms 48044 KB Output is correct
57 Correct 200 ms 32736 KB Output is correct
58 Correct 94 ms 27192 KB Output is correct
59 Correct 228 ms 32320 KB Output is correct
60 Correct 211 ms 33176 KB Output is correct
61 Correct 240 ms 32332 KB Output is correct
62 Correct 19 ms 13500 KB Output is correct
63 Correct 133 ms 31300 KB Output is correct
64 Correct 77 ms 21736 KB Output is correct
65 Correct 4 ms 9608 KB Output is correct
66 Correct 5 ms 9832 KB Output is correct
67 Correct 140 ms 33252 KB Output is correct
68 Correct 233 ms 32380 KB Output is correct
69 Correct 86 ms 25296 KB Output is correct
70 Correct 5 ms 9940 KB Output is correct
71 Correct 127 ms 26868 KB Output is correct
72 Correct 4 ms 9684 KB Output is correct
73 Correct 184 ms 32392 KB Output is correct
74 Correct 98 ms 30160 KB Output is correct
75 Correct 9 ms 10964 KB Output is correct
76 Correct 38 ms 19404 KB Output is correct
77 Correct 105 ms 36608 KB Output is correct
78 Correct 223 ms 33068 KB Output is correct
79 Correct 4 ms 9700 KB Output is correct
80 Correct 202 ms 38416 KB Output is correct
81 Correct 5 ms 9812 KB Output is correct
82 Correct 153 ms 32376 KB Output is correct
83 Correct 5 ms 9812 KB Output is correct
84 Correct 5 ms 9620 KB Output is correct
85 Correct 35 ms 18700 KB Output is correct
86 Correct 5 ms 9964 KB Output is correct
87 Correct 6 ms 9940 KB Output is correct
88 Correct 8 ms 10252 KB Output is correct
89 Correct 194 ms 33028 KB Output is correct
90 Correct 246 ms 32432 KB Output is correct
91 Correct 207 ms 37524 KB Output is correct
92 Correct 4 ms 9684 KB Output is correct