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Submission #702161

# Submission time Handle Problem Language Result Execution time Memory
702161 2023-02-23T06:55:40 Z LittleCube Network (BOI15_net) C++17
63 / 100
 10 ms 14804 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;

int n, pre[300005], sz[300005], cnt;
vector<int> E[300005], leaf;
vector<pii> ans;

void dfs(int u)
{
    sz[u] = (E[u].size() == 1);
    for (auto v : E[u])
        if(pre[u] != v)
        {
            pre[v] = u;
            dfs(v);
            sz[u] += sz[v];
        }
}

void collect(int u)
{
    if(E[u].size() == 1)
        leaf.emplace_back(u);
    for (auto v : E[u])
        if(pre[u] != v)
        {
            pre[v] = u;
            collect(v);
        }
}

signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    cin >> n;
    for (int i = 1; i < n; i++)
    {
        int u, v;
        cin >> u >> v;
        E[u].emplace_back(v);
        E[v].emplace_back(u);
    }
    dfs(1);
    int c = 1;
    for (int i = 1; i <= n; i++)
    {
        bool flag = (sz[1] - sz[i] <= sz[1] / 2);
        for(auto j : E[i])
            if(pre[i] != j && sz[j] > sz[1] / 2)
                flag = 0;
        if(flag)
            c = i;
    }
    pre[c] = 0;
    collect(c);
    for (int i = 0; i < sz[1] / 2; i++)
        ans.emplace_back(pii(leaf[i], leaf[i + (sz[1] + 1) / 2]));
    if(sz[1] & 1)
        ans.emplace_back(pii(c, leaf[sz[1] / 2]));
    cout << ans.size() << '\n';
    for(auto [i, j] : ans)
        cout << i << ' ' << j << '\n';
}

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7380 KB Output is correct
2 Correct 4 ms 7380 KB Output is correct
3 Correct 4 ms 7380 KB Output is correct
4 Correct 4 ms 7320 KB Output is correct
5 Correct 4 ms 7380 KB Output is correct
6 Correct 4 ms 7380 KB Output is correct
7 Correct 4 ms 7380 KB Output is correct
8 Correct 4 ms 7252 KB Output is correct
9 Correct 4 ms 7252 KB Output is correct
10 Correct 4 ms 7380 KB Output is correct
11 Correct 4 ms 7380 KB Output is correct
12 Correct 4 ms 7380 KB Output is correct
13 Correct 4 ms 7380 KB Output is correct
14 Correct 4 ms 7380 KB Output is correct
15 Correct 4 ms 7380 KB Output is correct
16 Correct 4 ms 7376 KB Output is correct
17 Correct 4 ms 7380 KB Output is correct
18 Correct 4 ms 7388 KB Output is correct
19 Correct 3 ms 7276 KB Output is correct
20 Correct 4 ms 7384 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7380 KB Output is correct
2 Correct 4 ms 7380 KB Output is correct
3 Correct 4 ms 7380 KB Output is correct
4 Correct 4 ms 7320 KB Output is correct
5 Correct 4 ms 7380 KB Output is correct
6 Correct 4 ms 7380 KB Output is correct
7 Correct 4 ms 7380 KB Output is correct
8 Correct 4 ms 7252 KB Output is correct
9 Correct 4 ms 7252 KB Output is correct
10 Correct 4 ms 7380 KB Output is correct
11 Correct 4 ms 7380 KB Output is correct
12 Correct 4 ms 7380 KB Output is correct
13 Correct 4 ms 7380 KB Output is correct
14 Correct 4 ms 7380 KB Output is correct
15 Correct 4 ms 7380 KB Output is correct
16 Correct 4 ms 7376 KB Output is correct
17 Correct 4 ms 7380 KB Output is correct
18 Correct 4 ms 7388 KB Output is correct
19 Correct 3 ms 7276 KB Output is correct
20 Correct 4 ms 7384 KB Output is correct
21 Correct 4 ms 7380 KB Output is correct
22 Correct 4 ms 7508 KB Output is correct
23 Correct 4 ms 7508 KB Output is correct
24 Correct 4 ms 7484 KB Output is correct
25 Correct 4 ms 7380 KB Output is correct
26 Correct 4 ms 7388 KB Output is correct
27 Correct 5 ms 7396 KB Output is correct
28 Correct 4 ms 7508 KB Output is correct
29 Correct 4 ms 7380 KB Output is correct
30 Correct 4 ms 7384 KB Output is correct
31 Correct 5 ms 7508 KB Output is correct
32 Correct 4 ms 7380 KB Output is correct
33 Correct 3 ms 7380 KB Output is correct
34 Correct 4 ms 7380 KB Output is correct
35 Correct 3 ms 7380 KB Output is correct
36 Correct 5 ms 7380 KB Output is correct
37 Correct 4 ms 7384 KB Output is correct
38 Correct 4 ms 7380 KB Output is correct
39 Correct 4 ms 7380 KB Output is correct
40 Correct 4 ms 7384 KB Output is correct
41 Correct 4 ms 7380 KB Output is correct
42 Correct 4 ms 7380 KB Output is correct
43 Correct 4 ms 7380 KB Output is correct
44 Correct 4 ms 7376 KB Output is correct
45 Correct 5 ms 7376 KB Output is correct
46 Correct 4 ms 7380 KB Output is correct
47 Correct 5 ms 7380 KB Output is correct
48 Correct 4 ms 7380 KB Output is correct
49 Correct 4 ms 7380 KB Output is correct
50 Correct 3 ms 7380 KB Output is correct
51 Correct 4 ms 7388 KB Output is correct
52 Correct 4 ms 7380 KB Output is correct
53 Correct 4 ms 7380 KB Output is correct
54 Correct 4 ms 7288 KB Output is correct
55 Correct 3 ms 7380 KB Output is correct
56 Correct 6 ms 7340 KB Output is correct
57 Correct 4 ms 7380 KB Output is correct
58 Correct 4 ms 7520 KB Output is correct

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7380 KB Output is correct
2 Correct 4 ms 7380 KB Output is correct
3 Correct 4 ms 7380 KB Output is correct
4 Correct 4 ms 7320 KB Output is correct
5 Correct 4 ms 7380 KB Output is correct
6 Correct 4 ms 7380 KB Output is correct
7 Correct 4 ms 7380 KB Output is correct
8 Correct 4 ms 7252 KB Output is correct
9 Correct 4 ms 7252 KB Output is correct
10 Correct 4 ms 7380 KB Output is correct
11 Correct 4 ms 7380 KB Output is correct
12 Correct 4 ms 7380 KB Output is correct
13 Correct 4 ms 7380 KB Output is correct
14 Correct 4 ms 7380 KB Output is correct
15 Correct 4 ms 7380 KB Output is correct
16 Correct 4 ms 7376 KB Output is correct
17 Correct 4 ms 7380 KB Output is correct
18 Correct 4 ms 7388 KB Output is correct
19 Correct 3 ms 7276 KB Output is correct
20 Correct 4 ms 7384 KB Output is correct
21 Correct 4 ms 7380 KB Output is correct
22 Correct 4 ms 7508 KB Output is correct
23 Correct 4 ms 7508 KB Output is correct
24 Correct 4 ms 7484 KB Output is correct
25 Correct 4 ms 7380 KB Output is correct
26 Correct 4 ms 7388 KB Output is correct
27 Correct 5 ms 7396 KB Output is correct
28 Correct 4 ms 7508 KB Output is correct
29 Correct 4 ms 7380 KB Output is correct
30 Correct 4 ms 7384 KB Output is correct
31 Correct 5 ms 7508 KB Output is correct
32 Correct 4 ms 7380 KB Output is correct
33 Correct 3 ms 7380 KB Output is correct
34 Correct 4 ms 7380 KB Output is correct
35 Correct 3 ms 7380 KB Output is correct
36 Correct 5 ms 7380 KB Output is correct
37 Correct 4 ms 7384 KB Output is correct
38 Correct 4 ms 7380 KB Output is correct
39 Correct 4 ms 7380 KB Output is correct
40 Correct 4 ms 7384 KB Output is correct
41 Correct 4 ms 7380 KB Output is correct
42 Correct 4 ms 7380 KB Output is correct
43 Correct 4 ms 7380 KB Output is correct
44 Correct 4 ms 7376 KB Output is correct
45 Correct 5 ms 7376 KB Output is correct
46 Correct 4 ms 7380 KB Output is correct
47 Correct 5 ms 7380 KB Output is correct
48 Correct 4 ms 7380 KB Output is correct
49 Correct 4 ms 7380 KB Output is correct
50 Correct 3 ms 7380 KB Output is correct
51 Correct 4 ms 7388 KB Output is correct
52 Correct 4 ms 7380 KB Output is correct
53 Correct 4 ms 7380 KB Output is correct
54 Correct 4 ms 7288 KB Output is correct
55 Correct 3 ms 7380 KB Output is correct
56 Correct 6 ms 7340 KB Output is correct
57 Correct 4 ms 7380 KB Output is correct
58 Correct 4 ms 7520 KB Output is correct
59 Runtime error 10 ms 14804 KB Execution killed with signal 11
60 Halted 0 ms 0 KB -