Submission #347074

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
347074	2021-01-11T16:52:11 Z	patrikpavic2	Network (BOI15_net)	C++17	100 / 100	605 ms	85352 KB

#include <cstdio>
#include <vector>

#define X first
#define Y second
#define PB push_back

using namespace std;

typedef pair < int, int > pii;
typedef vector < int > vi;

const int N = 1e6 + 500;

vector < pii > sol;
vector < int > v[N];
int n, root;

vi dfs(int x, int lst){
	if((int)v[x].size() == 1) return {x};
	vi ret;
	for(int y : v[x]){
		if(y == lst) continue;
		vi nxt = dfs(y, x);
		if((int)nxt.size() == 1){
			if((int)ret.size() > 1){
				sol.PB({nxt[0], ret.back()});
				ret.pop_back();
			}
			else
				ret.PB(nxt[0]);
		}
		else{
			if((int)ret.size() > 0){
				sol.PB({nxt[0], ret.back()});
				ret.pop_back();
				ret.PB(nxt[1]);
			}
			else{
				ret.PB(nxt[0]); 
				ret.PB(nxt[1]);
			}
		}
	}
	//printf("x = %d ret = %d\n", x, (int)ret.size());
	if(lst == x){
		if((int)ret.size() == 2)
			sol.PB({ret[0], ret[1]});
		else
			sol.PB({ret[0], x});
	}
	return ret;
}

int main(){
	scanf("%d", &n);
	for(int i = 1;i < n;i++){
		int x, y; scanf("%d%d", &x, &y);
		v[x].PB(y), v[y].PB(x);
	}
	root = 1;
	while((int)v[root].size() == 1) root++;
	dfs(root, root);
	printf("%d\n", (int)sol.size());
	for(pii tmp : sol)
		printf("%d %d\n", tmp.X, tmp.Y);
	return 0;
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:56:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   56 |  scanf("%d", &n);
      |  ~~~~~^~~~~~~~~~
net.cpp:58:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   58 |   int x, y; scanf("%d%d", &x, &y);
      |             ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	18 ms	23788 KB	Output is correct
2	Correct	16 ms	23788 KB	Output is correct
3	Correct	16 ms	23788 KB	Output is correct
4	Correct	16 ms	23808 KB	Output is correct
5	Correct	16 ms	23788 KB	Output is correct
6	Correct	16 ms	23788 KB	Output is correct
7	Correct	16 ms	23788 KB	Output is correct
8	Correct	17 ms	23788 KB	Output is correct
9	Correct	17 ms	23788 KB	Output is correct
10	Correct	16 ms	23788 KB	Output is correct
11	Correct	16 ms	23788 KB	Output is correct
12	Correct	17 ms	23788 KB	Output is correct
13	Correct	16 ms	23788 KB	Output is correct
14	Correct	18 ms	23788 KB	Output is correct
15	Correct	16 ms	23788 KB	Output is correct
16	Correct	17 ms	23788 KB	Output is correct
17	Correct	17 ms	23788 KB	Output is correct
18	Correct	17 ms	23788 KB	Output is correct
19	Correct	17 ms	23788 KB	Output is correct
20	Correct	17 ms	23788 KB	Output is correct

Subtask #2
45.0 / 45.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	18 ms	23788 KB	Output is correct
2	Correct	16 ms	23788 KB	Output is correct
3	Correct	16 ms	23788 KB	Output is correct
4	Correct	16 ms	23808 KB	Output is correct
5	Correct	16 ms	23788 KB	Output is correct
6	Correct	16 ms	23788 KB	Output is correct
7	Correct	16 ms	23788 KB	Output is correct
8	Correct	17 ms	23788 KB	Output is correct
9	Correct	17 ms	23788 KB	Output is correct
10	Correct	16 ms	23788 KB	Output is correct
11	Correct	16 ms	23788 KB	Output is correct
12	Correct	17 ms	23788 KB	Output is correct
13	Correct	16 ms	23788 KB	Output is correct
14	Correct	18 ms	23788 KB	Output is correct
15	Correct	16 ms	23788 KB	Output is correct
16	Correct	17 ms	23788 KB	Output is correct
17	Correct	17 ms	23788 KB	Output is correct
18	Correct	17 ms	23788 KB	Output is correct
19	Correct	17 ms	23788 KB	Output is correct
20	Correct	17 ms	23788 KB	Output is correct
21	Correct	16 ms	23788 KB	Output is correct
22	Correct	17 ms	23916 KB	Output is correct
23	Correct	18 ms	23916 KB	Output is correct
24	Correct	17 ms	23916 KB	Output is correct
25	Correct	17 ms	23916 KB	Output is correct
26	Correct	20 ms	23916 KB	Output is correct
27	Correct	18 ms	23916 KB	Output is correct
28	Correct	17 ms	23916 KB	Output is correct
29	Correct	17 ms	23916 KB	Output is correct
30	Correct	17 ms	23788 KB	Output is correct
31	Correct	17 ms	23916 KB	Output is correct
32	Correct	17 ms	23788 KB	Output is correct
33	Correct	17 ms	23788 KB	Output is correct
34	Correct	16 ms	23788 KB	Output is correct
35	Correct	17 ms	23808 KB	Output is correct
36	Correct	17 ms	23788 KB	Output is correct
37	Correct	17 ms	23916 KB	Output is correct
38	Correct	17 ms	23916 KB	Output is correct
39	Correct	16 ms	23788 KB	Output is correct
40	Correct	17 ms	23788 KB	Output is correct
41	Correct	18 ms	23788 KB	Output is correct
42	Correct	17 ms	23788 KB	Output is correct
43	Correct	17 ms	23788 KB	Output is correct
44	Correct	18 ms	23788 KB	Output is correct
45	Correct	17 ms	23788 KB	Output is correct
46	Correct	17 ms	23788 KB	Output is correct
47	Correct	17 ms	23788 KB	Output is correct
48	Correct	16 ms	23788 KB	Output is correct
49	Correct	17 ms	23788 KB	Output is correct
50	Correct	18 ms	24064 KB	Output is correct
51	Correct	17 ms	23660 KB	Output is correct
52	Correct	16 ms	23788 KB	Output is correct
53	Correct	17 ms	23916 KB	Output is correct
54	Correct	16 ms	23788 KB	Output is correct
55	Correct	17 ms	23808 KB	Output is correct
56	Correct	17 ms	23788 KB	Output is correct
57	Correct	16 ms	23788 KB	Output is correct
58	Correct	17 ms	23936 KB	Output is correct

Subtask #3
37.0 / 37.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	18 ms	23788 KB	Output is correct
2	Correct	16 ms	23788 KB	Output is correct
3	Correct	16 ms	23788 KB	Output is correct
4	Correct	16 ms	23808 KB	Output is correct
5	Correct	16 ms	23788 KB	Output is correct
6	Correct	16 ms	23788 KB	Output is correct
7	Correct	16 ms	23788 KB	Output is correct
8	Correct	17 ms	23788 KB	Output is correct
9	Correct	17 ms	23788 KB	Output is correct
10	Correct	16 ms	23788 KB	Output is correct
11	Correct	16 ms	23788 KB	Output is correct
12	Correct	17 ms	23788 KB	Output is correct
13	Correct	16 ms	23788 KB	Output is correct
14	Correct	18 ms	23788 KB	Output is correct
15	Correct	16 ms	23788 KB	Output is correct
16	Correct	17 ms	23788 KB	Output is correct
17	Correct	17 ms	23788 KB	Output is correct
18	Correct	17 ms	23788 KB	Output is correct
19	Correct	17 ms	23788 KB	Output is correct
20	Correct	17 ms	23788 KB	Output is correct
21	Correct	16 ms	23788 KB	Output is correct
22	Correct	17 ms	23916 KB	Output is correct
23	Correct	18 ms	23916 KB	Output is correct
24	Correct	17 ms	23916 KB	Output is correct
25	Correct	17 ms	23916 KB	Output is correct
26	Correct	20 ms	23916 KB	Output is correct
27	Correct	18 ms	23916 KB	Output is correct
28	Correct	17 ms	23916 KB	Output is correct
29	Correct	17 ms	23916 KB	Output is correct
30	Correct	17 ms	23788 KB	Output is correct
31	Correct	17 ms	23916 KB	Output is correct
32	Correct	17 ms	23788 KB	Output is correct
33	Correct	17 ms	23788 KB	Output is correct
34	Correct	16 ms	23788 KB	Output is correct
35	Correct	17 ms	23808 KB	Output is correct
36	Correct	17 ms	23788 KB	Output is correct
37	Correct	17 ms	23916 KB	Output is correct
38	Correct	17 ms	23916 KB	Output is correct
39	Correct	16 ms	23788 KB	Output is correct
40	Correct	17 ms	23788 KB	Output is correct
41	Correct	18 ms	23788 KB	Output is correct
42	Correct	17 ms	23788 KB	Output is correct
43	Correct	17 ms	23788 KB	Output is correct
44	Correct	18 ms	23788 KB	Output is correct
45	Correct	17 ms	23788 KB	Output is correct
46	Correct	17 ms	23788 KB	Output is correct
47	Correct	17 ms	23788 KB	Output is correct
48	Correct	16 ms	23788 KB	Output is correct
49	Correct	17 ms	23788 KB	Output is correct
50	Correct	18 ms	24064 KB	Output is correct
51	Correct	17 ms	23660 KB	Output is correct
52	Correct	16 ms	23788 KB	Output is correct
53	Correct	17 ms	23916 KB	Output is correct
54	Correct	16 ms	23788 KB	Output is correct
55	Correct	17 ms	23808 KB	Output is correct
56	Correct	17 ms	23788 KB	Output is correct
57	Correct	16 ms	23788 KB	Output is correct
58	Correct	17 ms	23936 KB	Output is correct
59	Correct	443 ms	47864 KB	Output is correct
60	Correct	541 ms	50532 KB	Output is correct
61	Correct	20 ms	23788 KB	Output is correct
62	Correct	19 ms	23788 KB	Output is correct
63	Correct	398 ms	45444 KB	Output is correct
64	Correct	19 ms	24684 KB	Output is correct
65	Correct	30 ms	27372 KB	Output is correct
66	Correct	202 ms	55660 KB	Output is correct
67	Correct	593 ms	83948 KB	Output is correct
68	Correct	605 ms	85352 KB	Output is correct
69	Correct	23 ms	24684 KB	Output is correct
70	Correct	124 ms	32996 KB	Output is correct
71	Correct	403 ms	53980 KB	Output is correct
72	Correct	414 ms	52576 KB	Output is correct
73	Correct	134 ms	30820 KB	Output is correct
74	Correct	541 ms	49512 KB	Output is correct
75	Correct	44 ms	26988 KB	Output is correct
76	Correct	403 ms	53452 KB	Output is correct
77	Correct	391 ms	53452 KB	Output is correct
78	Correct	52 ms	29292 KB	Output is correct
79	Correct	585 ms	78720 KB	Output is correct
80	Correct	18 ms	24044 KB	Output is correct
81	Correct	145 ms	33176 KB	Output is correct
82	Correct	470 ms	51292 KB	Output is correct
83	Correct	582 ms	49636 KB	Output is correct
84	Correct	530 ms	49512 KB	Output is correct
85	Correct	528 ms	49508 KB	Output is correct
86	Correct	538 ms	50532 KB	Output is correct
87	Correct	523 ms	50656 KB	Output is correct

Submission #347074

Compilation message

Subtask #1 18.0 / 18.0

Subtask #2 45.0 / 45.0

Subtask #3 37.0 / 37.0

Subtask #1
18.0 / 18.0

Subtask #2
45.0 / 45.0

Subtask #3
37.0 / 37.0