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Submission #656042

# Submission time Handle Problem Language Result Execution time Memory
656042 2022-11-06T09:01:09 Z mhn2 Network (BOI15_net) C++17
100 / 100
 789 ms 160724 KB 
#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define F first
#define S second
using namespace std;

const int N = 5e5+5;
vector<int> adj[N], lo[N], ch[N];
vector<pii> edge;

void dfs1(int v, int p) {
    for (int u : adj[v])
        if (u != p) {
            ch[v].push_back(u);
            dfs1(u, v);
        }
}

void dfs2(int v) {
    if (ch[v].size() == 0) {
        lo[v].push_back(v);
        return;
    }

    vector<int> a, b;
    for (int u : ch[v]) {
        dfs2(u);
        if (lo[u].size() == 2) {
            a.push_back(lo[u][0]);
            a.push_back(lo[u][1]);
        }
        else
            b.push_back(lo[u][0]);
    }
    for (int x : b)
        a.push_back(x);
    
    lo[v].push_back(a[0]);
    for (int i = 1; i < a.size()-1; i += 2)
        edge.push_back({a[i], a[i+1]});
    if (!(a.size() & 1))
        lo[v].push_back(a.back());
}

int main() {
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    int n, r;
    cin >> n;
    for (int i = 0; i < n-1; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for (r = 1; r <= n; r++)
        if (adj[r].size() == 1)
            break;

    dfs1(r, r);
    dfs2(r);

    for (int x : lo[r])
        edge.push_back({r, x});
    
    cout << edge.size() << endl;
    for (pii x : edge)
        cout << x.F << ' ' << x.S << endl;
}

Compilation message

net.cpp: In function 'void dfs2(int)':
net.cpp:41:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     for (int i = 1; i < a.size()-1; i += 2)
      |                     ~~^~~~~~~~~~~~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 35540 KB Output is correct
2 Correct 18 ms 35540 KB Output is correct
3 Correct 18 ms 35416 KB Output is correct
4 Correct 18 ms 35540 KB Output is correct
5 Correct 19 ms 35540 KB Output is correct
6 Correct 18 ms 35540 KB Output is correct
7 Correct 21 ms 35540 KB Output is correct
8 Correct 18 ms 35512 KB Output is correct
9 Correct 18 ms 35432 KB Output is correct
10 Correct 19 ms 35548 KB Output is correct
11 Correct 19 ms 35540 KB Output is correct
12 Correct 18 ms 35436 KB Output is correct
13 Correct 18 ms 35520 KB Output is correct
14 Correct 20 ms 35456 KB Output is correct
15 Correct 18 ms 35540 KB Output is correct
16 Correct 18 ms 35544 KB Output is correct
17 Correct 18 ms 35460 KB Output is correct
18 Correct 19 ms 35444 KB Output is correct
19 Correct 19 ms 35540 KB Output is correct
20 Correct 18 ms 35540 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 35540 KB Output is correct
2 Correct 18 ms 35540 KB Output is correct
3 Correct 18 ms 35416 KB Output is correct
4 Correct 18 ms 35540 KB Output is correct
5 Correct 19 ms 35540 KB Output is correct
6 Correct 18 ms 35540 KB Output is correct
7 Correct 21 ms 35540 KB Output is correct
8 Correct 18 ms 35512 KB Output is correct
9 Correct 18 ms 35432 KB Output is correct
10 Correct 19 ms 35548 KB Output is correct
11 Correct 19 ms 35540 KB Output is correct
12 Correct 18 ms 35436 KB Output is correct
13 Correct 18 ms 35520 KB Output is correct
14 Correct 20 ms 35456 KB Output is correct
15 Correct 18 ms 35540 KB Output is correct
16 Correct 18 ms 35544 KB Output is correct
17 Correct 18 ms 35460 KB Output is correct
18 Correct 19 ms 35444 KB Output is correct
19 Correct 19 ms 35540 KB Output is correct
20 Correct 18 ms 35540 KB Output is correct
21 Correct 17 ms 35468 KB Output is correct
22 Correct 20 ms 35676 KB Output is correct
23 Correct 19 ms 35660 KB Output is correct
24 Correct 22 ms 35604 KB Output is correct
25 Correct 20 ms 35696 KB Output is correct
26 Correct 19 ms 35608 KB Output is correct
27 Correct 21 ms 35660 KB Output is correct
28 Correct 20 ms 35724 KB Output is correct
29 Correct 24 ms 35660 KB Output is correct
30 Correct 18 ms 35540 KB Output is correct
31 Correct 23 ms 35716 KB Output is correct
32 Correct 18 ms 35548 KB Output is correct
33 Correct 18 ms 35540 KB Output is correct
34 Correct 17 ms 35540 KB Output is correct
35 Correct 20 ms 35464 KB Output is correct
36 Correct 18 ms 35540 KB Output is correct
37 Correct 18 ms 35552 KB Output is correct
38 Correct 19 ms 35668 KB Output is correct
39 Correct 22 ms 35540 KB Output is correct
40 Correct 18 ms 35520 KB Output is correct
41 Correct 20 ms 35524 KB Output is correct
42 Correct 19 ms 35540 KB Output is correct
43 Correct 18 ms 35540 KB Output is correct
44 Correct 19 ms 35540 KB Output is correct
45 Correct 18 ms 35548 KB Output is correct
46 Correct 19 ms 35540 KB Output is correct
47 Correct 17 ms 35540 KB Output is correct
48 Correct 18 ms 35472 KB Output is correct
49 Correct 20 ms 35600 KB Output is correct
50 Correct 17 ms 35552 KB Output is correct
51 Correct 19 ms 35464 KB Output is correct
52 Correct 18 ms 35580 KB Output is correct
53 Correct 19 ms 35680 KB Output is correct
54 Correct 17 ms 35544 KB Output is correct
55 Correct 17 ms 35540 KB Output is correct
56 Correct 18 ms 35548 KB Output is correct
57 Correct 19 ms 35716 KB Output is correct
58 Correct 21 ms 35608 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 35540 KB Output is correct
2 Correct 18 ms 35540 KB Output is correct
3 Correct 18 ms 35416 KB Output is correct
4 Correct 18 ms 35540 KB Output is correct
5 Correct 19 ms 35540 KB Output is correct
6 Correct 18 ms 35540 KB Output is correct
7 Correct 21 ms 35540 KB Output is correct
8 Correct 18 ms 35512 KB Output is correct
9 Correct 18 ms 35432 KB Output is correct
10 Correct 19 ms 35548 KB Output is correct
11 Correct 19 ms 35540 KB Output is correct
12 Correct 18 ms 35436 KB Output is correct
13 Correct 18 ms 35520 KB Output is correct
14 Correct 20 ms 35456 KB Output is correct
15 Correct 18 ms 35540 KB Output is correct
16 Correct 18 ms 35544 KB Output is correct
17 Correct 18 ms 35460 KB Output is correct
18 Correct 19 ms 35444 KB Output is correct
19 Correct 19 ms 35540 KB Output is correct
20 Correct 18 ms 35540 KB Output is correct
21 Correct 17 ms 35468 KB Output is correct
22 Correct 20 ms 35676 KB Output is correct
23 Correct 19 ms 35660 KB Output is correct
24 Correct 22 ms 35604 KB Output is correct
25 Correct 20 ms 35696 KB Output is correct
26 Correct 19 ms 35608 KB Output is correct
27 Correct 21 ms 35660 KB Output is correct
28 Correct 20 ms 35724 KB Output is correct
29 Correct 24 ms 35660 KB Output is correct
30 Correct 18 ms 35540 KB Output is correct
31 Correct 23 ms 35716 KB Output is correct
32 Correct 18 ms 35548 KB Output is correct
33 Correct 18 ms 35540 KB Output is correct
34 Correct 17 ms 35540 KB Output is correct
35 Correct 20 ms 35464 KB Output is correct
36 Correct 18 ms 35540 KB Output is correct
37 Correct 18 ms 35552 KB Output is correct
38 Correct 19 ms 35668 KB Output is correct
39 Correct 22 ms 35540 KB Output is correct
40 Correct 18 ms 35520 KB Output is correct
41 Correct 20 ms 35524 KB Output is correct
42 Correct 19 ms 35540 KB Output is correct
43 Correct 18 ms 35540 KB Output is correct
44 Correct 19 ms 35540 KB Output is correct
45 Correct 18 ms 35548 KB Output is correct
46 Correct 19 ms 35540 KB Output is correct
47 Correct 17 ms 35540 KB Output is correct
48 Correct 18 ms 35472 KB Output is correct
49 Correct 20 ms 35600 KB Output is correct
50 Correct 17 ms 35552 KB Output is correct
51 Correct 19 ms 35464 KB Output is correct
52 Correct 18 ms 35580 KB Output is correct
53 Correct 19 ms 35680 KB Output is correct
54 Correct 17 ms 35544 KB Output is correct
55 Correct 17 ms 35540 KB Output is correct
56 Correct 18 ms 35548 KB Output is correct
57 Correct 19 ms 35716 KB Output is correct
58 Correct 21 ms 35608 KB Output is correct
59 Correct 649 ms 74300 KB Output is correct
60 Correct 768 ms 77104 KB Output is correct
61 Correct 18 ms 35540 KB Output is correct
62 Correct 18 ms 35540 KB Output is correct
63 Correct 592 ms 69092 KB Output is correct
64 Correct 23 ms 36424 KB Output is correct
65 Correct 32 ms 41240 KB Output is correct
66 Correct 194 ms 77544 KB Output is correct
67 Correct 744 ms 160724 KB Output is correct
68 Correct 709 ms 126724 KB Output is correct
69 Correct 40 ms 36948 KB Output is correct
70 Correct 200 ms 50116 KB Output is correct
71 Correct 687 ms 77756 KB Output is correct
72 Correct 683 ms 78456 KB Output is correct
73 Correct 171 ms 47420 KB Output is correct
74 Correct 778 ms 78140 KB Output is correct
75 Correct 74 ms 40168 KB Output is correct
76 Correct 709 ms 76424 KB Output is correct
77 Correct 661 ms 76212 KB Output is correct
78 Correct 66 ms 42936 KB Output is correct
79 Correct 658 ms 134720 KB Output is correct
80 Correct 24 ms 35924 KB Output is correct
81 Correct 201 ms 49624 KB Output is correct
82 Correct 780 ms 77792 KB Output is correct
83 Correct 742 ms 78064 KB Output is correct
84 Correct 766 ms 78164 KB Output is correct
85 Correct 759 ms 78140 KB Output is correct
86 Correct 762 ms 76736 KB Output is correct
87 Correct 789 ms 76724 KB Output is correct