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Submission #779840

# Submission time Handle Problem Language Result Execution time Memory
779840 2023-07-12T00:34:45 Z GusterGoose27 Thousands Islands (IOI22_islands) C++17
100 / 100
 119 ms 23084 KB 
#include <bits/stdc++.h>

using namespace std;

const int MAXN = 1e5+5;
typedef pair<int, int> pii;

vector<pii> edges[MAXN];
vector<int> rev[MAXN];
bool dead[MAXN];
int deg[MAXN];
bool is_reversed[MAXN];
bool cyc[MAXN];
int vis[MAXN];
pii cnxt[MAXN];
pii cprv[MAXN];
bool cnt[2*MAXN];
int n, m;

void prune(int cur) {
    if (dead[cur] == 1) return;
    dead[cur] = 1;
    for (int prv: rev[cur]) {
        if (!dead[prv]) {
            deg[prv]--;
            if (deg[prv] == 0) prune(prv);
        }
    }
}

vector<int> stck;

pii find_cycle(int s, bool skip = 0) {
    vis[s] = max(vis[s], 1);
    stck.push_back(s);
    for (pii p: edges[s]) {
        if (dead[p.first]) continue;
        if (skip) {
            skip = 0;
            continue;
        }
        cnxt[s] = p;
        if (vis[p.first] == 2) {
            vis[s] = 2;
            return p;
        }
        cprv[p.first] = pii(s, p.second);
        if (vis[p.first] == 1) {
            while (stck.back() != p.first) {
                cyc[stck.back()] = 1;
                stck.pop_back();
            }
            cyc[p.first] = 1;
            vis[s] = 2;
            return p;
        }
        find_cycle(p.first);
        vis[s] = 2;
        return p;
    }
    assert(false);
}

void get_cyc(int s, vector<int> &v) {
    if (!cyc[s]) {
        v.push_back(cnxt[s].second);
        get_cyc(cnxt[s].first, v);
        v.push_back(cnxt[s].second);
        return;
    }
    int t = s;
    do {
        int orig = t;
        if (is_reversed[t]) {
            v.push_back(cprv[t].second);
            t = cprv[t].first;
        }
        else {
            v.push_back(cnxt[t].second);
            t = cnxt[t].first;
        }
        is_reversed[orig] ^= 1;
    } while (t != s);
    return;
}

variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
    n = N;
    m = M;
    for (int i = 0; i < m; i++) {
        edges[U[i]].push_back(pii(V[i], i));
        rev[V[i]].push_back(U[i]);
        deg[U[i]]++;
    }
    for (int i = 0; i < n; i++) if (deg[i] == 0) prune(i);
    if (dead[0]) return false;
    int s = 0;
    vector<int> res;
    vector<int> s_edges;
    while (deg[s] <= 1) {
        if (dead[s]) return false;
        prune(s);
        deg[s] = 0;
        for (pii nxt: edges[s]) {
            if (!dead[nxt.first]) {
                res.push_back(nxt.second);
                s_edges.push_back(nxt.second);
                s = nxt.first;
                break;
            }
        }
    }
    // return vector<int>();
    assert(deg[s] >= 2);
    pii e1 = find_cycle(s);
    stck.clear();
    pii e2 = find_cycle(s, 1);
    cnxt[s] = e1;
    get_cyc(s, res);
    res.push_back(e2.second);
    get_cyc(e2.first, res);
    res.push_back(e2.second);
    get_cyc(s, res);
    res.push_back(e2.second);
    get_cyc(e2.first, res);
    res.push_back(e2.second);
    reverse(s_edges.begin(), s_edges.end());
    for (int v: s_edges) res.push_back(v);
    int pos = 0;
    for (int v: res) {
        if (cnt[v] == 0) {
            assert(pos == U[v]);
            pos = V[v];
        }
        else {
            assert(pos == V[v]);
            pos = U[v];
        }
        cnt[v] ^= 1;
    }
    for (int i = 0; i < m; i++) assert(!cnt[i]);
    assert(res.size() < 2e6);
    for (int i = 0; i < res.size()-1; i++) assert(res[i] != res[i+1]);
    assert(!res.empty());
    return res;
}

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:143:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  143 |     for (int i = 0; i < res.size()-1; i++) assert(res[i] != res[i+1]);
      |                     ~~^~~~~~~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 4948 KB Output is correct
2 Correct 2 ms 4948 KB Output is correct
3 Correct 2 ms 4948 KB Output is correct
4 Correct 2 ms 4948 KB Output is correct
5 Correct 2 ms 4948 KB Output is correct
6 Correct 2 ms 4948 KB Output is correct
7 Correct 31 ms 11040 KB Output is correct

Subtask #2
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 5016 KB Output is correct
2 Correct 2 ms 4948 KB Output is correct
3 Correct 2 ms 4952 KB Output is correct
4 Correct 2 ms 4948 KB Output is correct
5 Correct 2 ms 4948 KB Output is correct
6 Correct 27 ms 10064 KB Output is correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5204 KB Output is correct
2 Correct 2 ms 4948 KB Output is correct
3 Correct 2 ms 4948 KB Output is correct
4 Correct 2 ms 4948 KB Output is correct
5 Correct 3 ms 5076 KB Output is correct
6 Correct 4 ms 4948 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 2 ms 4948 KB Output is correct
10 Correct 3 ms 5076 KB Output is correct
11 Correct 2 ms 4948 KB Output is correct
12 Correct 3 ms 5076 KB Output is correct
13 Correct 2 ms 4948 KB Output is correct
14 Correct 2 ms 4968 KB Output is correct
15 Correct 2 ms 4948 KB Output is correct
16 Correct 3 ms 4948 KB Output is correct
17 Correct 21 ms 8232 KB Output is correct
18 Correct 16 ms 7892 KB Output is correct
19 Correct 2 ms 4948 KB Output is correct
20 Correct 2 ms 4948 KB Output is correct
21 Correct 2 ms 4948 KB Output is correct
22 Correct 2 ms 4948 KB Output is correct
23 Correct 32 ms 10096 KB Output is correct

Subtask #4
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 4948 KB Output is correct
2 Correct 3 ms 5076 KB Output is correct
3 Correct 29 ms 10648 KB Output is correct
4 Correct 34 ms 11016 KB Output is correct
5 Correct 3 ms 5076 KB Output is correct
6 Correct 3 ms 5076 KB Output is correct
7 Correct 2 ms 4948 KB Output is correct
8 Correct 2 ms 4948 KB Output is correct
9 Correct 2 ms 4948 KB Output is correct
10 Correct 4 ms 5204 KB Output is correct
11 Correct 3 ms 5204 KB Output is correct
12 Correct 3 ms 5204 KB Output is correct
13 Correct 3 ms 5204 KB Output is correct
14 Correct 3 ms 5204 KB Output is correct
15 Correct 4 ms 5204 KB Output is correct
16 Correct 3 ms 5076 KB Output is correct
17 Correct 2 ms 4948 KB Output is correct
18 Correct 3 ms 5204 KB Output is correct
19 Correct 3 ms 5076 KB Output is correct
20 Correct 32 ms 11436 KB Output is correct
21 Correct 31 ms 11152 KB Output is correct
22 Correct 3 ms 5076 KB Output is correct
23 Correct 2 ms 4948 KB Output is correct
24 Correct 3 ms 4948 KB Output is correct
25 Correct 3 ms 5044 KB Output is correct
26 Correct 3 ms 5204 KB Output is correct
27 Correct 33 ms 11480 KB Output is correct
28 Correct 32 ms 11596 KB Output is correct
29 Correct 2 ms 4948 KB Output is correct
30 Correct 37 ms 12032 KB Output is correct
31 Correct 2 ms 4948 KB Output is correct
32 Correct 31 ms 11536 KB Output is correct
33 Correct 33 ms 11108 KB Output is correct
34 Correct 18 ms 8220 KB Output is correct
35 Correct 3 ms 5076 KB Output is correct
36 Correct 28 ms 10484 KB Output is correct
37 Correct 33 ms 11740 KB Output is correct
38 Correct 3 ms 5076 KB Output is correct
39 Correct 27 ms 10448 KB Output is correct
40 Correct 3 ms 5076 KB Output is correct
41 Correct 34 ms 11952 KB Output is correct
42 Correct 35 ms 11728 KB Output is correct
43 Correct 2 ms 4948 KB Output is correct
44 Correct 3 ms 5076 KB Output is correct
45 Correct 3 ms 5272 KB Output is correct
46 Correct 15 ms 7816 KB Output is correct

Subtask #5
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 4948 KB Output is correct
2 Correct 2 ms 4948 KB Output is correct
3 Correct 2 ms 4948 KB Output is correct
4 Correct 2 ms 4948 KB Output is correct
5 Correct 2 ms 4948 KB Output is correct
6 Correct 2 ms 4948 KB Output is correct
7 Correct 31 ms 11040 KB Output is correct
8 Correct 2 ms 5016 KB Output is correct
9 Correct 2 ms 4948 KB Output is correct
10 Correct 2 ms 4952 KB Output is correct
11 Correct 2 ms 4948 KB Output is correct
12 Correct 2 ms 4948 KB Output is correct
13 Correct 27 ms 10064 KB Output is correct
14 Correct 6 ms 5204 KB Output is correct
15 Correct 2 ms 4948 KB Output is correct
16 Correct 2 ms 4948 KB Output is correct
17 Correct 2 ms 4948 KB Output is correct
18 Correct 3 ms 5076 KB Output is correct
19 Correct 4 ms 4948 KB Output is correct
20 Correct 3 ms 4948 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 2 ms 4948 KB Output is correct
23 Correct 3 ms 5076 KB Output is correct
24 Correct 2 ms 4948 KB Output is correct
25 Correct 3 ms 5076 KB Output is correct
26 Correct 2 ms 4948 KB Output is correct
27 Correct 2 ms 4968 KB Output is correct
28 Correct 2 ms 4948 KB Output is correct
29 Correct 3 ms 4948 KB Output is correct
30 Correct 21 ms 8232 KB Output is correct
31 Correct 16 ms 7892 KB Output is correct
32 Correct 2 ms 4948 KB Output is correct
33 Correct 2 ms 4948 KB Output is correct
34 Correct 2 ms 4948 KB Output is correct
35 Correct 2 ms 4948 KB Output is correct
36 Correct 32 ms 10096 KB Output is correct
37 Correct 2 ms 4948 KB Output is correct
38 Correct 2 ms 4948 KB Output is correct
39 Correct 3 ms 4948 KB Output is correct
40 Correct 2 ms 4948 KB Output is correct
41 Correct 16 ms 7892 KB Output is correct
42 Correct 4 ms 5204 KB Output is correct
43 Correct 32 ms 12692 KB Output is correct
44 Correct 30 ms 12568 KB Output is correct
45 Correct 31 ms 12696 KB Output is correct
46 Correct 2 ms 4948 KB Output is correct
47 Correct 2 ms 4948 KB Output is correct
48 Correct 3 ms 4948 KB Output is correct
49 Correct 3 ms 5204 KB Output is correct
50 Correct 119 ms 23084 KB Output is correct
51 Correct 83 ms 20516 KB Output is correct
52 Correct 65 ms 20288 KB Output is correct
53 Correct 68 ms 21660 KB Output is correct
54 Correct 66 ms 20256 KB Output is correct
55 Correct 68 ms 20256 KB Output is correct
56 Correct 87 ms 20424 KB Output is correct
57 Correct 47 ms 13684 KB Output is correct
58 Correct 77 ms 19188 KB Output is correct
59 Correct 64 ms 14896 KB Output is correct
60 Correct 62 ms 14540 KB Output is correct
61 Correct 65 ms 14376 KB Output is correct
62 Correct 13 ms 7124 KB Output is correct
63 Correct 56 ms 14412 KB Output is correct
64 Correct 21 ms 8788 KB Output is correct
65 Correct 2 ms 4948 KB Output is correct
66 Correct 3 ms 5076 KB Output is correct
67 Correct 61 ms 17048 KB Output is correct
68 Correct 37 ms 12040 KB Output is correct
69 Correct 34 ms 12500 KB Output is correct
70 Correct 3 ms 5184 KB Output is correct
71 Correct 43 ms 11596 KB Output is correct
72 Correct 2 ms 4948 KB Output is correct
73 Correct 71 ms 13860 KB Output is correct
74 Correct 97 ms 22780 KB Output is correct
75 Correct 5 ms 5460 KB Output is correct
76 Correct 37 ms 13276 KB Output is correct
77 Correct 41 ms 17824 KB Output is correct
78 Correct 65 ms 14512 KB Output is correct
79 Correct 2 ms 4948 KB Output is correct
80 Correct 106 ms 22044 KB Output is correct
81 Correct 4 ms 5204 KB Output is correct
82 Correct 38 ms 11156 KB Output is correct
83 Correct 3 ms 5076 KB Output is correct
84 Correct 2 ms 4948 KB Output is correct
85 Correct 32 ms 11956 KB Output is correct
86 Correct 3 ms 5204 KB Output is correct
87 Correct 3 ms 5460 KB Output is correct
88 Correct 4 ms 5328 KB Output is correct
89 Correct 60 ms 14504 KB Output is correct
90 Correct 63 ms 14412 KB Output is correct
91 Correct 111 ms 20400 KB Output is correct
92 Correct 2 ms 4948 KB Output is correct