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Submission #702162

# Submission time Handle Problem Language Result Execution time Memory
702162 2023-02-23T06:56:22 Z LittleCube Network (BOI15_net) C++14
100 / 100
 535 ms 61660 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[500005], sz[500005], cnt;
vector<int> E[500005], 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';
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:67:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   67 |     for(auto [i, j] : ans)
      |              ^

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 8 ms 11988 KB Output is correct
4 Correct 6 ms 11988 KB Output is correct
5 Correct 6 ms 11988 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 6 ms 11988 KB Output is correct
8 Correct 6 ms 11988 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 6 ms 11988 KB Output is correct
11 Correct 6 ms 11988 KB Output is correct
12 Correct 6 ms 12084 KB Output is correct
13 Correct 6 ms 11984 KB Output is correct
14 Correct 6 ms 11988 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 6 ms 11988 KB Output is correct
18 Correct 6 ms 11988 KB Output is correct
19 Correct 7 ms 11988 KB Output is correct
20 Correct 8 ms 11988 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 8 ms 11988 KB Output is correct
4 Correct 6 ms 11988 KB Output is correct
5 Correct 6 ms 11988 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 6 ms 11988 KB Output is correct
8 Correct 6 ms 11988 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 6 ms 11988 KB Output is correct
11 Correct 6 ms 11988 KB Output is correct
12 Correct 6 ms 12084 KB Output is correct
13 Correct 6 ms 11984 KB Output is correct
14 Correct 6 ms 11988 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 6 ms 11988 KB Output is correct
18 Correct 6 ms 11988 KB Output is correct
19 Correct 7 ms 11988 KB Output is correct
20 Correct 8 ms 11988 KB Output is correct
21 Correct 6 ms 11988 KB Output is correct
22 Correct 7 ms 12116 KB Output is correct
23 Correct 7 ms 12116 KB Output is correct
24 Correct 7 ms 12116 KB Output is correct
25 Correct 7 ms 12116 KB Output is correct
26 Correct 7 ms 12160 KB Output is correct
27 Correct 8 ms 12116 KB Output is correct
28 Correct 7 ms 12116 KB Output is correct
29 Correct 8 ms 12116 KB Output is correct
30 Correct 8 ms 11988 KB Output is correct
31 Correct 7 ms 12116 KB Output is correct
32 Correct 6 ms 12080 KB Output is correct
33 Correct 6 ms 11988 KB Output is correct
34 Correct 6 ms 12016 KB Output is correct
35 Correct 6 ms 12080 KB Output is correct
36 Correct 6 ms 11988 KB Output is correct
37 Correct 7 ms 12116 KB Output is correct
38 Correct 7 ms 12116 KB Output is correct
39 Correct 7 ms 12036 KB Output is correct
40 Correct 7 ms 12076 KB Output is correct
41 Correct 6 ms 11988 KB Output is correct
42 Correct 6 ms 11988 KB Output is correct
43 Correct 6 ms 12116 KB Output is correct
44 Correct 6 ms 11988 KB Output is correct
45 Correct 7 ms 11988 KB Output is correct
46 Correct 6 ms 12116 KB Output is correct
47 Correct 6 ms 11988 KB Output is correct
48 Correct 7 ms 11988 KB Output is correct
49 Correct 6 ms 12116 KB Output is correct
50 Correct 9 ms 11988 KB Output is correct
51 Correct 7 ms 11988 KB Output is correct
52 Correct 6 ms 11988 KB Output is correct
53 Correct 7 ms 12116 KB Output is correct
54 Correct 6 ms 12028 KB Output is correct
55 Correct 6 ms 11988 KB Output is correct
56 Correct 6 ms 12084 KB Output is correct
57 Correct 6 ms 11988 KB Output is correct
58 Correct 7 ms 12216 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 8 ms 11988 KB Output is correct
4 Correct 6 ms 11988 KB Output is correct
5 Correct 6 ms 11988 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 6 ms 11988 KB Output is correct
8 Correct 6 ms 11988 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 6 ms 11988 KB Output is correct
11 Correct 6 ms 11988 KB Output is correct
12 Correct 6 ms 12084 KB Output is correct
13 Correct 6 ms 11984 KB Output is correct
14 Correct 6 ms 11988 KB Output is correct
15 Correct 6 ms 11988 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 6 ms 11988 KB Output is correct
18 Correct 6 ms 11988 KB Output is correct
19 Correct 7 ms 11988 KB Output is correct
20 Correct 8 ms 11988 KB Output is correct
21 Correct 6 ms 11988 KB Output is correct
22 Correct 7 ms 12116 KB Output is correct
23 Correct 7 ms 12116 KB Output is correct
24 Correct 7 ms 12116 KB Output is correct
25 Correct 7 ms 12116 KB Output is correct
26 Correct 7 ms 12160 KB Output is correct
27 Correct 8 ms 12116 KB Output is correct
28 Correct 7 ms 12116 KB Output is correct
29 Correct 8 ms 12116 KB Output is correct
30 Correct 8 ms 11988 KB Output is correct
31 Correct 7 ms 12116 KB Output is correct
32 Correct 6 ms 12080 KB Output is correct
33 Correct 6 ms 11988 KB Output is correct
34 Correct 6 ms 12016 KB Output is correct
35 Correct 6 ms 12080 KB Output is correct
36 Correct 6 ms 11988 KB Output is correct
37 Correct 7 ms 12116 KB Output is correct
38 Correct 7 ms 12116 KB Output is correct
39 Correct 7 ms 12036 KB Output is correct
40 Correct 7 ms 12076 KB Output is correct
41 Correct 6 ms 11988 KB Output is correct
42 Correct 6 ms 11988 KB Output is correct
43 Correct 6 ms 12116 KB Output is correct
44 Correct 6 ms 11988 KB Output is correct
45 Correct 7 ms 11988 KB Output is correct
46 Correct 6 ms 12116 KB Output is correct
47 Correct 6 ms 11988 KB Output is correct
48 Correct 7 ms 11988 KB Output is correct
49 Correct 6 ms 12116 KB Output is correct
50 Correct 9 ms 11988 KB Output is correct
51 Correct 7 ms 11988 KB Output is correct
52 Correct 6 ms 11988 KB Output is correct
53 Correct 7 ms 12116 KB Output is correct
54 Correct 6 ms 12028 KB Output is correct
55 Correct 6 ms 11988 KB Output is correct
56 Correct 6 ms 12084 KB Output is correct
57 Correct 6 ms 11988 KB Output is correct
58 Correct 7 ms 12216 KB Output is correct
59 Correct 360 ms 40632 KB Output is correct
60 Correct 459 ms 43952 KB Output is correct
61 Correct 6 ms 11988 KB Output is correct
62 Correct 6 ms 11988 KB Output is correct
63 Correct 273 ms 37932 KB Output is correct
64 Correct 8 ms 12628 KB Output is correct
65 Correct 16 ms 14616 KB Output is correct
66 Correct 151 ms 34588 KB Output is correct
67 Correct 535 ms 61660 KB Output is correct
68 Correct 526 ms 60408 KB Output is correct
69 Correct 11 ms 13116 KB Output is correct
70 Correct 101 ms 23060 KB Output is correct
71 Correct 265 ms 47672 KB Output is correct
72 Correct 312 ms 46392 KB Output is correct
73 Correct 87 ms 20464 KB Output is correct
74 Correct 441 ms 42612 KB Output is correct
75 Correct 25 ms 15944 KB Output is correct
76 Correct 302 ms 47400 KB Output is correct
77 Correct 276 ms 47516 KB Output is correct
78 Correct 30 ms 16340 KB Output is correct
79 Correct 514 ms 56268 KB Output is correct
80 Correct 8 ms 12244 KB Output is correct
81 Correct 94 ms 23076 KB Output is correct
82 Correct 364 ms 44852 KB Output is correct
83 Correct 458 ms 42516 KB Output is correct
84 Correct 436 ms 42524 KB Output is correct
85 Correct 426 ms 42552 KB Output is correct
86 Correct 396 ms 44000 KB Output is correct
87 Correct 416 ms 43972 KB Output is correct