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Submission #706645

# Submission time Handle Problem Language Result Execution time Memory
706645 2023-03-07T09:06:19 Z danikoynov Thousands Islands (IOI22_islands) C++17
100 / 100
 167 ms 29964 KB 
#include "islands.h"

#include <variant>
#include <vector>
#include <queue>
#include <iostream>
using namespace std;

const int maxn = 1e5 + 10;
int seen[maxn], in_deg[maxn], out_deg[maxn];
int n, m;
vector < int > links[maxn], rev_links[maxn];
vector < pair < int, int > > graph[maxn];
vector < int > path[3], cycle[3];

int dfs(int node, int id, int root)
{
    if (seen[node] != 0)
        return node;
    ///cout << node << " : " << id << " : " << root << endl;
    seen[node] = 1;
    for (pair < int, int > dest : graph[node])
    {
        if (seen[dest.first] >= 0)
        {
            path[id].push_back(dest.second);
            int up = dfs(dest.first, id, root);
            if (id == 0)
            {
                if (up >= 0)
                {
                    path[id].pop_back();
                    cycle[id].push_back(dest.second);
                    seen[node] = 2;
                }
                else
                    seen[node] = 0;
                if (node != root)
                {
                    if (up == node)
                        return - 1;
                    else
                        return up;
                }
            }
            if (up >= 0 && seen[up] == 1)
            {
                path[id].pop_back();
                cycle[id].push_back(dest.second);
                if (node != root)
                {
                    if (up == node)
                        return -1;
                    else
                        return up;
                }
            }

            if (node != root || id == 1)
                return up;

            id ++;
        }
    }
    return -1;
}

int clear_useless()
{
    queue < int > q;
    for (int i = 0; i < n; i ++)
    {
        if (!out_deg[i])
            q.push(i);
    }

    int start = 0;
    while(!q.empty() || out_deg[start] <= 1)
    {
        if (!q.empty())
        {
            int node = q.front();
            q.pop();
            seen[node] = -1;
            for (int dest : rev_links[node])
            {
                out_deg[dest] --;
                if (out_deg[dest] == 0)
                    q.push(dest);
            }
        }
        while(out_deg[start] <= 1)
        {
            seen[start] = -1;
            out_deg[start] = 0;
            for (int dest : rev_links[start])
            {
                out_deg[dest] --;
                if (out_deg[dest] == 0)
                    q.push(dest);
            }

            pair < int, int > nxt = make_pair(-1, 0);
            for (pair < int, int > cur : graph[start])
            {
                if (seen[cur.first] != -1)
                {
                    nxt = cur;
                    break;
                }
            }

            if (nxt.first == -1)
                return -1;
            start = nxt.first;
            path[2].push_back(nxt.second);
        }
    }

    return start;
}

void append_to_end(vector < int > &base, vector < int > &to_add, int type)
{
    if (type == 0)
    {
        for (int i = 0; i < to_add.size(); i ++)
            base.push_back(to_add[i]);
    }
    else
    {
        for (int i = (int)(to_add.size()) - 1; i >= 0; i --)
            base.push_back(to_add[i]);
    }
}

std::variant<bool, std::vector<int>> find_journey(int N, int M, std::vector<int> U, std::vector<int> V)
{
    n = N;
    m = M;
    for (int i = 0; i < M; i ++)
    {
        links[U[i]].push_back(V[i]);
        rev_links[V[i]].push_back(U[i]);
        in_deg[V[i]] ++;
        out_deg[U[i]] ++;

        graph[U[i]].push_back({V[i], i});
    }

    int root = clear_useless();
    if (root < 0)
        return false;

    dfs(root, 0, root);
       /** for (int i = 0; i < cycle[1].size(); i  ++)
            cout << cycle[1][i] << " ";
        cout << endl;
        exit(0);*/
    vector < int > ans;
    append_to_end(ans, path[2], 0);
    append_to_end(ans, path[0], 0);
    append_to_end(ans, cycle[0], 1);
    append_to_end(ans, path[0], 1);
    append_to_end(ans, path[1], 0);

    if (cycle[1].empty())
    {
        int ver = V[path[1].back()];
        int idx = 0;
        while(V[cycle[0][idx]] != ver)
            idx ++;
            ///cout << "here " << U[cycle[0][idx]] << " " << V[]
        for (int i = idx; i < cycle[0].size(); i ++)
        ans.push_back(cycle[0][i]);
        for (int i = 0; i < idx; i ++)
            ans.push_back(cycle[0][i]);
    }
    else
        append_to_end(ans, cycle[1], 1);

    append_to_end(ans, path[1], 1);
    if (!cycle[1].empty())
    {
        append_to_end(ans, path[0], 0);
        append_to_end(ans, cycle[0], 0);
        append_to_end(ans, path[0], 1);
        append_to_end(ans, path[1], 0);
        append_to_end(ans, cycle[1], 0);
        append_to_end(ans, path[1], 1);
    }
    append_to_end(ans, path[2], 1);
    return ans;
}

Compilation message

islands.cpp: In function 'void append_to_end(std::vector<int>&, std::vector<int>&, int)':
islands.cpp:127:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  127 |         for (int i = 0; i < to_add.size(); i ++)
      |                         ~~^~~~~~~~~~~~~~~
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:174:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  174 |         for (int i = idx; i < cycle[0].size(); i ++)
      |                           ~~^~~~~~~~~~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7252 KB Output is correct
2 Correct 4 ms 7352 KB Output is correct
3 Correct 4 ms 7252 KB Output is correct
4 Correct 4 ms 7252 KB Output is correct
5 Correct 4 ms 7352 KB Output is correct
6 Correct 5 ms 7280 KB Output is correct
7 Correct 42 ms 15072 KB Output is correct

Subtask #2
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7252 KB Output is correct
2 Correct 4 ms 7252 KB Output is correct
3 Correct 3 ms 7352 KB Output is correct
4 Correct 4 ms 7348 KB Output is correct
5 Correct 4 ms 7252 KB Output is correct
6 Correct 40 ms 14208 KB Output is correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 7508 KB Output is correct
2 Correct 5 ms 7252 KB Output is correct
3 Correct 4 ms 7348 KB Output is correct
4 Correct 4 ms 7252 KB Output is correct
5 Correct 5 ms 7508 KB Output is correct
6 Correct 4 ms 7352 KB Output is correct
7 Correct 4 ms 7380 KB Output is correct
8 Correct 4 ms 7352 KB Output is correct
9 Correct 4 ms 7352 KB Output is correct
10 Correct 4 ms 7532 KB Output is correct
11 Correct 4 ms 7252 KB Output is correct
12 Correct 5 ms 7508 KB Output is correct
13 Correct 4 ms 7252 KB Output is correct
14 Correct 4 ms 7252 KB Output is correct
15 Correct 4 ms 7356 KB Output is correct
16 Correct 4 ms 7380 KB Output is correct
17 Correct 27 ms 11832 KB Output is correct
18 Correct 22 ms 11424 KB Output is correct
19 Correct 4 ms 7328 KB Output is correct
20 Correct 4 ms 7348 KB Output is correct
21 Correct 4 ms 7252 KB Output is correct
22 Correct 4 ms 7252 KB Output is correct
23 Correct 38 ms 14168 KB Output is correct

Subtask #4
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 7380 KB Output is correct
2 Correct 6 ms 7488 KB Output is correct
3 Correct 39 ms 14828 KB Output is correct
4 Correct 42 ms 15188 KB Output is correct
5 Correct 5 ms 7492 KB Output is correct
6 Correct 5 ms 7508 KB Output is correct
7 Correct 4 ms 7352 KB Output is correct
8 Correct 4 ms 7348 KB Output is correct
9 Correct 4 ms 7352 KB Output is correct
10 Correct 5 ms 7636 KB Output is correct
11 Correct 5 ms 7508 KB Output is correct
12 Correct 5 ms 7508 KB Output is correct
13 Correct 5 ms 7636 KB Output is correct
14 Correct 5 ms 7492 KB Output is correct
15 Correct 6 ms 7636 KB Output is correct
16 Correct 4 ms 7508 KB Output is correct
17 Correct 4 ms 7252 KB Output is correct
18 Correct 5 ms 7508 KB Output is correct
19 Correct 6 ms 7368 KB Output is correct
20 Correct 42 ms 15788 KB Output is correct
21 Correct 42 ms 15380 KB Output is correct
22 Correct 5 ms 7508 KB Output is correct
23 Correct 4 ms 7380 KB Output is correct
24 Correct 4 ms 7252 KB Output is correct
25 Correct 4 ms 7380 KB Output is correct
26 Correct 5 ms 7636 KB Output is correct
27 Correct 46 ms 15892 KB Output is correct
28 Correct 47 ms 16000 KB Output is correct
29 Correct 4 ms 7256 KB Output is correct
30 Correct 48 ms 16668 KB Output is correct
31 Correct 5 ms 7256 KB Output is correct
32 Correct 43 ms 15788 KB Output is correct
33 Correct 41 ms 15492 KB Output is correct
34 Correct 26 ms 11856 KB Output is correct
35 Correct 4 ms 7512 KB Output is correct
36 Correct 39 ms 14648 KB Output is correct
37 Correct 44 ms 16828 KB Output is correct
38 Correct 5 ms 7380 KB Output is correct
39 Correct 38 ms 14908 KB Output is correct
40 Correct 4 ms 7508 KB Output is correct
41 Correct 49 ms 17224 KB Output is correct
42 Correct 46 ms 16720 KB Output is correct
43 Correct 4 ms 7252 KB Output is correct
44 Correct 5 ms 7508 KB Output is correct
45 Correct 5 ms 7620 KB Output is correct
46 Correct 24 ms 11280 KB Output is correct

Subtask #5
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7252 KB Output is correct
2 Correct 4 ms 7352 KB Output is correct
3 Correct 4 ms 7252 KB Output is correct
4 Correct 4 ms 7252 KB Output is correct
5 Correct 4 ms 7352 KB Output is correct
6 Correct 5 ms 7280 KB Output is correct
7 Correct 42 ms 15072 KB Output is correct
8 Correct 4 ms 7252 KB Output is correct
9 Correct 4 ms 7252 KB Output is correct
10 Correct 3 ms 7352 KB Output is correct
11 Correct 4 ms 7348 KB Output is correct
12 Correct 4 ms 7252 KB Output is correct
13 Correct 40 ms 14208 KB Output is correct
14 Correct 5 ms 7508 KB Output is correct
15 Correct 5 ms 7252 KB Output is correct
16 Correct 4 ms 7348 KB Output is correct
17 Correct 4 ms 7252 KB Output is correct
18 Correct 5 ms 7508 KB Output is correct
19 Correct 4 ms 7352 KB Output is correct
20 Correct 4 ms 7380 KB Output is correct
21 Correct 4 ms 7352 KB Output is correct
22 Correct 4 ms 7352 KB Output is correct
23 Correct 4 ms 7532 KB Output is correct
24 Correct 4 ms 7252 KB Output is correct
25 Correct 5 ms 7508 KB Output is correct
26 Correct 4 ms 7252 KB Output is correct
27 Correct 4 ms 7252 KB Output is correct
28 Correct 4 ms 7356 KB Output is correct
29 Correct 4 ms 7380 KB Output is correct
30 Correct 27 ms 11832 KB Output is correct
31 Correct 22 ms 11424 KB Output is correct
32 Correct 4 ms 7328 KB Output is correct
33 Correct 4 ms 7348 KB Output is correct
34 Correct 4 ms 7252 KB Output is correct
35 Correct 4 ms 7252 KB Output is correct
36 Correct 38 ms 14168 KB Output is correct
37 Correct 4 ms 7252 KB Output is correct
38 Correct 4 ms 7252 KB Output is correct
39 Correct 4 ms 7352 KB Output is correct
40 Correct 4 ms 7380 KB Output is correct
41 Correct 25 ms 11120 KB Output is correct
42 Correct 6 ms 7556 KB Output is correct
43 Correct 61 ms 15800 KB Output is correct
44 Correct 53 ms 15676 KB Output is correct
45 Correct 53 ms 15664 KB Output is correct
46 Correct 4 ms 7252 KB Output is correct
47 Correct 4 ms 7352 KB Output is correct
48 Correct 4 ms 7252 KB Output is correct
49 Correct 5 ms 7584 KB Output is correct
50 Correct 141 ms 29420 KB Output is correct
51 Correct 120 ms 23120 KB Output is correct
52 Correct 134 ms 23092 KB Output is correct
53 Correct 121 ms 23200 KB Output is correct
54 Correct 126 ms 23464 KB Output is correct
55 Correct 132 ms 23484 KB Output is correct
56 Correct 117 ms 23588 KB Output is correct
57 Correct 91 ms 20076 KB Output is correct
58 Correct 114 ms 27432 KB Output is correct
59 Correct 143 ms 21944 KB Output is correct
60 Correct 141 ms 21232 KB Output is correct
61 Correct 134 ms 21572 KB Output is correct
62 Correct 25 ms 10964 KB Output is correct
63 Correct 123 ms 21104 KB Output is correct
64 Correct 30 ms 12472 KB Output is correct
65 Correct 4 ms 7352 KB Output is correct
66 Correct 4 ms 7380 KB Output is correct
67 Correct 145 ms 22152 KB Output is correct
68 Correct 51 ms 16724 KB Output is correct
69 Correct 76 ms 17484 KB Output is correct
70 Correct 5 ms 7636 KB Output is correct
71 Correct 79 ms 16828 KB Output is correct
72 Correct 4 ms 7252 KB Output is correct
73 Correct 120 ms 20368 KB Output is correct
74 Correct 123 ms 29964 KB Output is correct
75 Correct 7 ms 8020 KB Output is correct
76 Correct 43 ms 18216 KB Output is correct
77 Correct 88 ms 20988 KB Output is correct
78 Correct 126 ms 20804 KB Output is correct
79 Correct 4 ms 7252 KB Output is correct
80 Correct 167 ms 28212 KB Output is correct
81 Correct 4 ms 7508 KB Output is correct
82 Correct 39 ms 15148 KB Output is correct
83 Correct 4 ms 7380 KB Output is correct
84 Correct 4 ms 7344 KB Output is correct
85 Correct 54 ms 17188 KB Output is correct
86 Correct 5 ms 7508 KB Output is correct
87 Correct 6 ms 8404 KB Output is correct
88 Correct 5 ms 7636 KB Output is correct
89 Correct 126 ms 19788 KB Output is correct
90 Correct 141 ms 20140 KB Output is correct
91 Correct 151 ms 27048 KB Output is correct
92 Correct 3 ms 7252 KB Output is correct