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Submission #394759

# Submission time Handle Problem Language Result Execution time Memory
394759 2021-04-27T09:33:19 Z Saynaa Network (BOI15_net) C++14
100 / 100
 496 ms 41040 KB 
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN = 5e5 + 10;
int n;
vector< int > adj[MAXN], ls;

void dfs(int u, int p = -1){
	if( adj[u].size() == 1) ls.push_back(u);
	for(int i = 0; i < adj[u].size(); i ++){
		int v = adj[u][i];
		if( v == p) continue;
		dfs(v, u);
	}
}

int main(){
	ios_base::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, u --, v --;
		adj[u].push_back(v), adj[v].push_back(u);
	}
	dfs(0);
	cout << (ls.size() + 1)/2 << '\n';
//	int pt = 0;
	for(int i = 0; i + ls.size()/2 < ls.size(); i ++){
		cout << ls[i] + 1 << " " << ls[i + ls.size()/2] + 1 << '\n';
		//pt = i;
	}
	//if( ls.size() % 2)
	return 0;
}

Compilation message

net.cpp: In function 'void dfs(int, int)':
net.cpp:10:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |  for(int i = 0; i < adj[u].size(); i ++){
      |                 ~~^~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 9 ms 11980 KB Output is correct
3 Correct 8 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 8 ms 11980 KB Output is correct
6 Correct 8 ms 11984 KB Output is correct
7 Correct 8 ms 11980 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 8 ms 12052 KB Output is correct
10 Correct 8 ms 11980 KB Output is correct
11 Correct 8 ms 11980 KB Output is correct
12 Correct 8 ms 11980 KB Output is correct
13 Correct 8 ms 11968 KB Output is correct
14 Correct 8 ms 11980 KB Output is correct
15 Correct 8 ms 11980 KB Output is correct
16 Correct 8 ms 11980 KB Output is correct
17 Correct 8 ms 11984 KB Output is correct
18 Correct 8 ms 11980 KB Output is correct
19 Correct 8 ms 11980 KB Output is correct
20 Correct 8 ms 11980 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 9 ms 11980 KB Output is correct
3 Correct 8 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 8 ms 11980 KB Output is correct
6 Correct 8 ms 11984 KB Output is correct
7 Correct 8 ms 11980 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 8 ms 12052 KB Output is correct
10 Correct 8 ms 11980 KB Output is correct
11 Correct 8 ms 11980 KB Output is correct
12 Correct 8 ms 11980 KB Output is correct
13 Correct 8 ms 11968 KB Output is correct
14 Correct 8 ms 11980 KB Output is correct
15 Correct 8 ms 11980 KB Output is correct
16 Correct 8 ms 11980 KB Output is correct
17 Correct 8 ms 11984 KB Output is correct
18 Correct 8 ms 11980 KB Output is correct
19 Correct 8 ms 11980 KB Output is correct
20 Correct 8 ms 11980 KB Output is correct
21 Correct 7 ms 11980 KB Output is correct
22 Correct 8 ms 12152 KB Output is correct
23 Correct 8 ms 12108 KB Output is correct
24 Correct 8 ms 12056 KB Output is correct
25 Correct 10 ms 12108 KB Output is correct
26 Correct 8 ms 12108 KB Output is correct
27 Correct 9 ms 12108 KB Output is correct
28 Correct 9 ms 12108 KB Output is correct
29 Correct 8 ms 12108 KB Output is correct
30 Correct 8 ms 11984 KB Output is correct
31 Correct 9 ms 12144 KB Output is correct
32 Correct 8 ms 11980 KB Output is correct
33 Correct 8 ms 11980 KB Output is correct
34 Correct 8 ms 11980 KB Output is correct
35 Correct 8 ms 11980 KB Output is correct
36 Correct 7 ms 11980 KB Output is correct
37 Correct 8 ms 11980 KB Output is correct
38 Correct 8 ms 12108 KB Output is correct
39 Correct 8 ms 11980 KB Output is correct
40 Correct 8 ms 11980 KB Output is correct
41 Correct 10 ms 12012 KB Output is correct
42 Correct 8 ms 11980 KB Output is correct
43 Correct 8 ms 11980 KB Output is correct
44 Correct 8 ms 11996 KB Output is correct
45 Correct 8 ms 11980 KB Output is correct
46 Correct 8 ms 12096 KB Output is correct
47 Correct 8 ms 11980 KB Output is correct
48 Correct 8 ms 11980 KB Output is correct
49 Correct 8 ms 12108 KB Output is correct
50 Correct 8 ms 11980 KB Output is correct
51 Correct 8 ms 11980 KB Output is correct
52 Correct 8 ms 11980 KB Output is correct
53 Correct 8 ms 11980 KB Output is correct
54 Correct 10 ms 11980 KB Output is correct
55 Correct 8 ms 12076 KB Output is correct
56 Correct 9 ms 12032 KB Output is correct
57 Correct 10 ms 11980 KB Output is correct
58 Correct 9 ms 12108 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 11980 KB Output is correct
2 Correct 9 ms 11980 KB Output is correct
3 Correct 8 ms 11980 KB Output is correct
4 Correct 8 ms 11980 KB Output is correct
5 Correct 8 ms 11980 KB Output is correct
6 Correct 8 ms 11984 KB Output is correct
7 Correct 8 ms 11980 KB Output is correct
8 Correct 8 ms 11980 KB Output is correct
9 Correct 8 ms 12052 KB Output is correct
10 Correct 8 ms 11980 KB Output is correct
11 Correct 8 ms 11980 KB Output is correct
12 Correct 8 ms 11980 KB Output is correct
13 Correct 8 ms 11968 KB Output is correct
14 Correct 8 ms 11980 KB Output is correct
15 Correct 8 ms 11980 KB Output is correct
16 Correct 8 ms 11980 KB Output is correct
17 Correct 8 ms 11984 KB Output is correct
18 Correct 8 ms 11980 KB Output is correct
19 Correct 8 ms 11980 KB Output is correct
20 Correct 8 ms 11980 KB Output is correct
21 Correct 7 ms 11980 KB Output is correct
22 Correct 8 ms 12152 KB Output is correct
23 Correct 8 ms 12108 KB Output is correct
24 Correct 8 ms 12056 KB Output is correct
25 Correct 10 ms 12108 KB Output is correct
26 Correct 8 ms 12108 KB Output is correct
27 Correct 9 ms 12108 KB Output is correct
28 Correct 9 ms 12108 KB Output is correct
29 Correct 8 ms 12108 KB Output is correct
30 Correct 8 ms 11984 KB Output is correct
31 Correct 9 ms 12144 KB Output is correct
32 Correct 8 ms 11980 KB Output is correct
33 Correct 8 ms 11980 KB Output is correct
34 Correct 8 ms 11980 KB Output is correct
35 Correct 8 ms 11980 KB Output is correct
36 Correct 7 ms 11980 KB Output is correct
37 Correct 8 ms 11980 KB Output is correct
38 Correct 8 ms 12108 KB Output is correct
39 Correct 8 ms 11980 KB Output is correct
40 Correct 8 ms 11980 KB Output is correct
41 Correct 10 ms 12012 KB Output is correct
42 Correct 8 ms 11980 KB Output is correct
43 Correct 8 ms 11980 KB Output is correct
44 Correct 8 ms 11996 KB Output is correct
45 Correct 8 ms 11980 KB Output is correct
46 Correct 8 ms 12096 KB Output is correct
47 Correct 8 ms 11980 KB Output is correct
48 Correct 8 ms 11980 KB Output is correct
49 Correct 8 ms 12108 KB Output is correct
50 Correct 8 ms 11980 KB Output is correct
51 Correct 8 ms 11980 KB Output is correct
52 Correct 8 ms 11980 KB Output is correct
53 Correct 8 ms 11980 KB Output is correct
54 Correct 10 ms 11980 KB Output is correct
55 Correct 8 ms 12076 KB Output is correct
56 Correct 9 ms 12032 KB Output is correct
57 Correct 10 ms 11980 KB Output is correct
58 Correct 9 ms 12108 KB Output is correct
59 Correct 357 ms 30084 KB Output is correct
60 Correct 428 ms 32056 KB Output is correct
61 Correct 8 ms 11980 KB Output is correct
62 Correct 8 ms 11980 KB Output is correct
63 Correct 310 ms 28292 KB Output is correct
64 Correct 9 ms 12364 KB Output is correct
65 Correct 18 ms 13644 KB Output is correct
66 Correct 131 ms 25544 KB Output is correct
67 Correct 496 ms 40260 KB Output is correct
68 Correct 483 ms 41040 KB Output is correct
69 Correct 16 ms 12748 KB Output is correct
70 Correct 94 ms 19096 KB Output is correct
71 Correct 316 ms 35228 KB Output is correct
72 Correct 328 ms 34332 KB Output is correct
73 Correct 84 ms 17348 KB Output is correct
74 Correct 436 ms 31104 KB Output is correct
75 Correct 31 ms 14648 KB Output is correct
76 Correct 345 ms 34784 KB Output is correct
77 Correct 321 ms 35220 KB Output is correct
78 Correct 32 ms 14660 KB Output is correct
79 Correct 488 ms 38440 KB Output is correct
80 Correct 9 ms 12236 KB Output is correct
81 Correct 112 ms 19120 KB Output is correct
82 Correct 380 ms 33108 KB Output is correct
83 Correct 452 ms 31028 KB Output is correct
84 Correct 432 ms 30964 KB Output is correct
85 Correct 430 ms 31160 KB Output is correct
86 Correct 429 ms 32184 KB Output is correct
87 Correct 448 ms 32032 KB Output is correct