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Submission #137109

# Submission time Handle Problem Language Result Execution time Memory
137109 2019-07-27T05:32:52 Z silxikys Network (BOI15_net) C++14
100 / 100
 617 ms 55416 KB 
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
 
const int maxn = 5e5+5;
int n;
vector<int> adj[maxn];
int deg[maxn];
int tin[maxn];
int pt = 0;
 
void dfs(int i, int p) {
    tin[i] = pt++;
    for (int j: adj[i]) {
        if (j == p) continue;
        dfs(j,i);
    }
}
 
int main()
{
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    cin >> n;
    for (int i = 0; i < n - 1; i++) {
        int a, b; cin >> a >> b;
        ++deg[a];
        ++deg[b];
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    vector<int> leafs;
    int start = 1;
    for (int i = 1; i <= n; i++) {
        if (deg[i] == 1) leafs.push_back(i);
        if (deg[i] > 1) {
            start = i;
        }
    }
    dfs(start,start);
    sort(leafs.begin(),leafs.end(),[](auto a, auto b) {
            return tin[a] < tin[b];
            });
    vector<pair<int,int>> ans;
    int k = leafs.size();
    int m = k/2;
    cout << (k+1)/2 << '\n';
    for (int i = 0; i < (k+1)/2; i++) {
        cout << leafs[i] << ' ' << leafs[(i+m)%k] << '\n';
    }
}

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 12152 KB Output is correct
2 Correct 13 ms 12024 KB Output is correct
3 Correct 13 ms 12152 KB Output is correct
4 Correct 13 ms 12024 KB Output is correct
5 Correct 13 ms 12152 KB Output is correct
6 Correct 13 ms 12152 KB Output is correct
7 Correct 12 ms 12152 KB Output is correct
8 Correct 13 ms 12024 KB Output is correct
9 Correct 13 ms 12152 KB Output is correct
10 Correct 13 ms 12024 KB Output is correct
11 Correct 13 ms 12152 KB Output is correct
12 Correct 13 ms 12152 KB Output is correct
13 Correct 13 ms 12024 KB Output is correct
14 Correct 13 ms 12152 KB Output is correct
15 Correct 12 ms 12024 KB Output is correct
16 Correct 13 ms 12152 KB Output is correct
17 Correct 12 ms 12152 KB Output is correct
18 Correct 12 ms 12152 KB Output is correct
19 Correct 12 ms 12024 KB Output is correct
20 Correct 13 ms 12152 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 12152 KB Output is correct
2 Correct 13 ms 12024 KB Output is correct
3 Correct 13 ms 12152 KB Output is correct
4 Correct 13 ms 12024 KB Output is correct
5 Correct 13 ms 12152 KB Output is correct
6 Correct 13 ms 12152 KB Output is correct
7 Correct 12 ms 12152 KB Output is correct
8 Correct 13 ms 12024 KB Output is correct
9 Correct 13 ms 12152 KB Output is correct
10 Correct 13 ms 12024 KB Output is correct
11 Correct 13 ms 12152 KB Output is correct
12 Correct 13 ms 12152 KB Output is correct
13 Correct 13 ms 12024 KB Output is correct
14 Correct 13 ms 12152 KB Output is correct
15 Correct 12 ms 12024 KB Output is correct
16 Correct 13 ms 12152 KB Output is correct
17 Correct 12 ms 12152 KB Output is correct
18 Correct 12 ms 12152 KB Output is correct
19 Correct 12 ms 12024 KB Output is correct
20 Correct 13 ms 12152 KB Output is correct
21 Correct 13 ms 12024 KB Output is correct
22 Correct 14 ms 12280 KB Output is correct
23 Correct 15 ms 12192 KB Output is correct
24 Correct 14 ms 12280 KB Output is correct
25 Correct 14 ms 12280 KB Output is correct
26 Correct 14 ms 12156 KB Output is correct
27 Correct 13 ms 12152 KB Output is correct
28 Correct 18 ms 12284 KB Output is correct
29 Correct 13 ms 12152 KB Output is correct
30 Correct 13 ms 12152 KB Output is correct
31 Correct 17 ms 12152 KB Output is correct
32 Correct 15 ms 12024 KB Output is correct
33 Correct 13 ms 12152 KB Output is correct
34 Correct 13 ms 12024 KB Output is correct
35 Correct 13 ms 12100 KB Output is correct
36 Correct 13 ms 12024 KB Output is correct
37 Correct 13 ms 12152 KB Output is correct
38 Correct 13 ms 12152 KB Output is correct
39 Correct 14 ms 12152 KB Output is correct
40 Correct 13 ms 12156 KB Output is correct
41 Correct 13 ms 12152 KB Output is correct
42 Correct 13 ms 12152 KB Output is correct
43 Correct 13 ms 12152 KB Output is correct
44 Correct 12 ms 12024 KB Output is correct
45 Correct 13 ms 12152 KB Output is correct
46 Correct 13 ms 12152 KB Output is correct
47 Correct 13 ms 12152 KB Output is correct
48 Correct 13 ms 12152 KB Output is correct
49 Correct 16 ms 12204 KB Output is correct
50 Correct 15 ms 12152 KB Output is correct
51 Correct 13 ms 12152 KB Output is correct
52 Correct 13 ms 12152 KB Output is correct
53 Correct 14 ms 12284 KB Output is correct
54 Correct 13 ms 12152 KB Output is correct
55 Correct 16 ms 12152 KB Output is correct
56 Correct 13 ms 12024 KB Output is correct
57 Correct 13 ms 12152 KB Output is correct
58 Correct 14 ms 12152 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 12152 KB Output is correct
2 Correct 13 ms 12024 KB Output is correct
3 Correct 13 ms 12152 KB Output is correct
4 Correct 13 ms 12024 KB Output is correct
5 Correct 13 ms 12152 KB Output is correct
6 Correct 13 ms 12152 KB Output is correct
7 Correct 12 ms 12152 KB Output is correct
8 Correct 13 ms 12024 KB Output is correct
9 Correct 13 ms 12152 KB Output is correct
10 Correct 13 ms 12024 KB Output is correct
11 Correct 13 ms 12152 KB Output is correct
12 Correct 13 ms 12152 KB Output is correct
13 Correct 13 ms 12024 KB Output is correct
14 Correct 13 ms 12152 KB Output is correct
15 Correct 12 ms 12024 KB Output is correct
16 Correct 13 ms 12152 KB Output is correct
17 Correct 12 ms 12152 KB Output is correct
18 Correct 12 ms 12152 KB Output is correct
19 Correct 12 ms 12024 KB Output is correct
20 Correct 13 ms 12152 KB Output is correct
21 Correct 13 ms 12024 KB Output is correct
22 Correct 14 ms 12280 KB Output is correct
23 Correct 15 ms 12192 KB Output is correct
24 Correct 14 ms 12280 KB Output is correct
25 Correct 14 ms 12280 KB Output is correct
26 Correct 14 ms 12156 KB Output is correct
27 Correct 13 ms 12152 KB Output is correct
28 Correct 18 ms 12284 KB Output is correct
29 Correct 13 ms 12152 KB Output is correct
30 Correct 13 ms 12152 KB Output is correct
31 Correct 17 ms 12152 KB Output is correct
32 Correct 15 ms 12024 KB Output is correct
33 Correct 13 ms 12152 KB Output is correct
34 Correct 13 ms 12024 KB Output is correct
35 Correct 13 ms 12100 KB Output is correct
36 Correct 13 ms 12024 KB Output is correct
37 Correct 13 ms 12152 KB Output is correct
38 Correct 13 ms 12152 KB Output is correct
39 Correct 14 ms 12152 KB Output is correct
40 Correct 13 ms 12156 KB Output is correct
41 Correct 13 ms 12152 KB Output is correct
42 Correct 13 ms 12152 KB Output is correct
43 Correct 13 ms 12152 KB Output is correct
44 Correct 12 ms 12024 KB Output is correct
45 Correct 13 ms 12152 KB Output is correct
46 Correct 13 ms 12152 KB Output is correct
47 Correct 13 ms 12152 KB Output is correct
48 Correct 13 ms 12152 KB Output is correct
49 Correct 16 ms 12204 KB Output is correct
50 Correct 15 ms 12152 KB Output is correct
51 Correct 13 ms 12152 KB Output is correct
52 Correct 13 ms 12152 KB Output is correct
53 Correct 14 ms 12284 KB Output is correct
54 Correct 13 ms 12152 KB Output is correct
55 Correct 16 ms 12152 KB Output is correct
56 Correct 13 ms 12024 KB Output is correct
57 Correct 13 ms 12152 KB Output is correct
58 Correct 14 ms 12152 KB Output is correct
59 Correct 462 ms 33932 KB Output is correct
60 Correct 553 ms 36356 KB Output is correct
61 Correct 12 ms 12024 KB Output is correct
62 Correct 13 ms 12152 KB Output is correct
63 Correct 395 ms 31692 KB Output is correct
64 Correct 15 ms 12536 KB Output is correct
65 Correct 26 ms 13816 KB Output is correct
66 Correct 171 ms 24440 KB Output is correct
67 Correct 617 ms 55416 KB Output is correct
68 Correct 583 ms 48368 KB Output is correct
69 Correct 22 ms 13048 KB Output is correct
70 Correct 136 ms 20616 KB Output is correct
71 Correct 434 ms 39468 KB Output is correct
72 Correct 439 ms 41568 KB Output is correct
73 Correct 126 ms 20212 KB Output is correct
74 Correct 576 ms 37996 KB Output is correct
75 Correct 51 ms 15736 KB Output is correct
76 Correct 435 ms 40832 KB Output is correct
77 Correct 462 ms 41112 KB Output is correct
78 Correct 50 ms 15856 KB Output is correct
79 Correct 564 ms 44476 KB Output is correct
80 Correct 16 ms 12280 KB Output is correct
81 Correct 148 ms 22772 KB Output is correct
82 Correct 501 ms 39144 KB Output is correct
83 Correct 577 ms 37160 KB Output is correct
84 Correct 567 ms 37216 KB Output is correct
85 Correct 558 ms 37076 KB Output is correct
86 Correct 567 ms 38252 KB Output is correct
87 Correct 549 ms 38108 KB Output is correct